src/compatibility/4.4/android-4.4-cdd.xhtml - fp2-dev/platform/docs/source.android.com - Gitiles

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 <h1>Android 4.4 Compatibility Definition</h1>
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 <span style="color: red; font-weight: bold;"><h2>Revision 1</h2></span><br/>
 <span style="color: red;">Last updated: July 23, 2013</span>
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 <p><b><font color="red">Revision 1</font></b><br/>
 Last updated: November 27, 2013
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 <p>Copyright &copy; 2013, Google Inc. All rights reserved.<br/>
 <a href="mailto:compatibility@android.com">compatibility@android.com</a>
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 <h2>Table of Contents</h2>
 <div style="margin-left: 2em;">
   <a href="#section-1">1. Introduction</a><br/>
   <a href="#section-2">2. Resources</a><br/>
   <a href="#section-3">3. Software</a><br/>
   <div style="margin-left: 2em;">
     <a href="#section-3.1">3.1. Managed API Compatibility</a><br/>
     <a href="#section-3.2">3.2. Soft API Compatibility</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-3.2.1">3.2.1. Permissions</a><br/>
       <a href="#section-3.2.2">3.2.2. Build Parameters</a><br/>
       <a href="#section-3.2.3">3.2.3. Intent Compatibility</a><br/>
       <div style="margin-left: 2em;">
         <a href="#section-3.2.3.1">3.2.3.1. Core Application Intents</a><br/>
         <a href="#section-3.2.3.2">3.2.3.2. Intent Overrides</a><br/>
         <a href="#section-3.2.3.3">3.2.3.3. Intent Namespaces</a><br/>
         <a href="#section-3.2.3.4">3.2.3.4. Broadcast Intents</a><br/>
         <a href="#section-3.2.3.5">3.2.3.5. Default App Settings</a><br/>
       </div>
     </div>
     <a href="#section-3.3">3.3. Native API Compatibility</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-3.3.1">3.3.1 Application Binary Interfaces</a><br/>
     </div>
     <a href="#section-3.4">3.4. Web Compatibility</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-3.4.1">3.4.1. WebView Compatibility</a><br/>
       <a href="#section-3.4.2">3.4.2. Browser Compatibility</a><br/>
     </div>
     <a href="#section-3.5">3.5. API Behavioral Compatibility</a><br/>
     <a href="#section-3.6">3.6. API Namespaces</a><br/>
     <a href="#section-3.7">3.7. Virtual Machine Compatibility</a><br/>
     <a href="#section-3.8">3.8. User Interface Compatibility</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-3.8.1">3.8.1. Launcher (Home Screen)</a><br/>
       <a href="#section-3.8.2">3.8.2. Widgets</a><br/>
       <a href="#section-3.8.3">3.8.3. Notifications</a><br/>
       <a href="#section-3.8.4">3.8.4. Search</a><br/>
       <a href="#section-3.8.5">3.8.5. Toasts</a><br/>
       <a href="#section-3.8.6">3.8.6. Themes</a><br/>
       <a href="#section-3.8.7">3.8.7. Live Wallpapers</a><br/>
       <a href="#section-3.8.8">3.8.8. Recent Application Display</a><br/>
       <a href="#section-3.8.9">3.8.9. Input Management</a><br/>
       <a href="#section-3.8.10">3.8.10. Lock Screen Media Remote Control</a><br/>
       <a href="#section-3.8.11">3.8.11. Dreams</a><br/>
       <a href="#section-3.8.12">3.8.12. Location</a><br/>
       <a href="#section-3.8.13">3.8.13. Unicode</a><br/>
     </div>
     <a href="#section-3.9">3.9 Device Administration</a><br/>
     <a href="#section-3.10">3.10 Accessibility</a><br/>
     <a href="#section-3.11">3.11 Text-to-Speech</a><br/>
   </div>
   <a href="#section-4">4. Application Packaging Compatibility</a><br/>
   <a href="#section-5">5. Multimedia Compatibility</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-5.1">5.1. Media Codecs</a><br/>
       <a href="#section-5.2">5.2. Video Encoding</a><br/>
       <a href="#section-5.3">5.3. Video Decoding</a><br/>
       <a href="#section-5.4">5.4. Audio Recording</a><br/>
       <a href="#section-5.5">5.5. Audio Latency</a><br/>
       <a href="#section-5.6">5.6. Network Protocols</a><br/>
     </div>
   <a href="#section-6">6. Developer Tools and Options Compatibility</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-6.1">6.1. Developer Tools</a><br/>
       <a href="#section-6.2">6.2. Developer Options</a><br/>
       <a href="#section-6.2.1">6.2.1. Experimental</a><br/>
     </div>
   <a href="#section-7">7. Hardware Compatibility</a><br/>
   <div style="margin-left: 2em;">
     <a href="#section-7.1">7.1. Display and Graphics</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-7.1.1">7.1.1. Screen Configuration</a><br/>
       <a href="#section-7.1.2">7.1.2. Display Metrics</a><br/>
       <a href="#section-7.1.3">7.1.3. Screen Orientation</a><br/>
       <a href="#section-7.1.4">7.1.4. 2D and 3D Graphics Acceleration</a><br/>
       <a href="#section-7.1.5">7.1.5. Legacy Application Compatibility Mode</a><br/>
       <a href="#section-7.1.6">7.1.6. Screen Types</a><br/>
       <a href="#section-7.1.7">7.1.7. Screen Technology</a><br/>
       <a href="#section-7.1.8">7.1.8. External Displays</a><br/>
     </div>
     <a href="#section-7.2">7.2. Input Devices</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-7.2.1">7.2.1. Keyboard</a><br/>
       <a href="#section-7.2.2">7.2.2. Non-touch Navigation</a><br/>
       <a href="#section-7.2.3">7.2.3. Navigation keys</a><br/>
       <a href="#section-7.2.4">7.2.4. Touchscreen input</a><br/>
       <a href="#section-7.2.5">7.2.5. Fake touch input</a><br/>
       <a href="#section-7.2.6">7.2.6. Microphone</a><br/>
     </div>
     <a href="#section-7.3">7.3. Sensors</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-7.3.1">7.3.1. Accelerometer</a><br/>
       <a href="#section-7.3.2">7.3.2. Magnetometer</a><br/>
       <a href="#section-7.3.3">7.3.3. GPS</a><br/>
       <a href="#section-7.3.4">7.3.4. Gyroscope</a><br/>
       <a href="#section-7.3.5">7.3.5. Barometer</a><br/>
       <a href="#section-7.3.6">7.3.6. Thermometer</a><br/>
       <a href="#section-7.3.7">7.3.7. Photometer</a><br/>
       <a href="#section-7.3.8">7.3.8. Proximity Sensor</a><br/>
     </div>
     <a href="#section-7.4">7.4. Data Connectivity</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-7.4.1">7.4.1. Telephony</a><br/>
       <a href="#section-7.4.2">7.4.2. IEEE 802.11 (Wi-Fi)</a><br/>
       <div style="margin-left: 2em;">
         <a href="#section-7.4.2.1">7.4.2.1. Wi-Fi Direct</a><br/>
         <a href="#section-7.4.2.2">7.4.2.2. Wi-Fi Tunneled Direct Link Setup</a><br/>
       </div>
       <a href="#section-7.4.3">7.4.3. Bluetooth</a><br/>
       <a href="#section-7.4.4">7.4.4. Near-Field Communications</a><br/>
       <a href="#section-7.4.5">7.4.5. Minimum Network Capability</a><br/>
       <a href="#section-7.4.6">7.4.6. Sync Settings</a><br/>
     </div>
     <a href="#section-7.5">7.5. Cameras</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-7.5.1">7.5.1. Rear-Facing Camera</a><br/>
       <a href="#section-7.5.2">7.5.2. Front-Facing Camera</a><br/>
       <a href="#section-7.5.3">7.5.3. Camera API Behavior</a><br/>
       <a href="#section-7.5.4">7.5.4. Camera Orientation</a><br/>
     </div>
     <a href="#section-7.6">7.6. Memory and Storage</a><br/>
     <div style="margin-left: 2em;">
       <a href="#section-7.6.1">7.6.1. Minimum Memory and Storage</a><br/>
       <a href="#section-7.6.2">7.6.2. Shared External Storage</a><br/>
     </div>
     <a href="#section-7.7">7.7. USB</a><br/>
   </div>
   <a href="#section-8">8. Performance Compatibility</a><br/>
   <a href="#section-9">9. Security Model Compatibility</a><br/>
   <div style="margin-left: 2em;">
     <a href="#section-9.1">9.1. Permissions</a><br/>
     <a href="#section-9.2">9.2. UID and Process Isolation</a><br/>
     <a href="#section-9.3">9.3. Filesystem Permissions</a><br/>
     <a href="#section-9.4">9.4. Alternate Execution Environments</a><br/>
     <a href="#section-9.5">9.5. Multi-User Support</a><br/>
     <a href="#section-9.6">9.6. Premium SMS Warning</a><br/>
     <a href="#section-9.7">9.7. Kernel Security Features</a><br/>
     <a href="#section-9.8">9.8. Privacy</a><br/>
     <a href="#section-9.9">9.9. Full-Disk Encryption</a><br/>
   </div>
   <a href="#section-10">10. Software Compatibility Testing</a><br/>
   <div style="margin-left: 2em;">
     <a href="#section-10.1">10.1. Compatibility Test Suite</a><br/>
     <a href="#section-10.2">10.2. CTS Verifier</a><br/>
     <a href="#section-10.3">10.3. Reference Applications</a><br/>
   </div>
   <a href="#section-11">11. Updatable Software</a><br/>
   <a href="#section-12">12. Document Changelog</a><br/>
   <a href="#section-13">13. Contact Us</a><br/>
 </div>

 <div style="page-break-before: always;"></div>

 <a name="section-1"></a><h2 id="section-1">1. Introduction</h2>
 <p>This document enumerates the requirements that must be met in order for
 devices to be compatible with Android 4.4.</p>
 <p>The use of "must", "must not", "required", "shall", "shall not", "should",
 "should not", "recommended", "may" and "optional" is per the IETF standard
 defined in RFC2119 [<a href="#resources01">Resources, 1</a>].</p>
 <p>As used in this document, a "device implementer" or "implementer" is a
 person or organization developing a hardware/software solution running Android
 4.4. A "device implementation" or "implementation" is the hardware/software
 solution so developed.</p>
 <p>To be considered compatible with Android 4.4, device implementations
 MUST meet the requirements presented in this Compatibility Definition,
 including any documents incorporated via reference.</p>
 <p>Where this definition or the software tests described in <a
 href="#section-10">Section 10</a> is silent, ambiguous, or incomplete, it is
 the responsibility of the device implementer to ensure compatibility with
 existing implementations.</p>
 <p>For this reason, the Android Open Source Project [<a
 href="#resources03">Resources, 3</a>] is both the reference and preferred
 implementation of Android. Device implementers are strongly encouraged to base
 their implementations to the greatest extent possible on the "upstream" source
 code available from the Android Open Source Project. While some components can
 hypothetically be replaced with alternate implementations this practice is
 strongly discouraged, as passing the software tests will become substantially
 more difficult. It is the implementer's responsibility to ensure full
 behavioral compatibility with the standard Android implementation, including
 and beyond the Compatibility Test Suite. Finally, note that certain component
 substitutions and modifications are explicitly forbidden by this document.</p>
 <a name="section-2"></a><h2 id="section-2">2. Resources</h2>
 <ol>
 <a name="resources01"></a><li id="resources01">IETF RFC2119 Requirement Levels: <a href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a></li>
 <a name="resources02"></a><li id="resources02">Android Compatibility Program Overview: <a href="http://source.android.com/compatibility/index.html">http://source.android.com/compatibility/index.html</a></li>
 <a name="resources03"></a><li id="resources03">Android Open Source Project: <a href="http://source.android.com/">http://source.android.com/</a></li>
 <a name="resources04"></a><li id="resources04">API definitions and documentation: <a href="http://developer.android.com/reference/packages.html">http://developer.android.com/reference/packages.html</a></li>
 <a name="resources05"></a><li id="resources05">Android Permissions reference: <a href="http://developer.android.com/reference/android/Manifest.permission.html">http://developer.android.com/reference/android/Manifest.permission.html</a></li>
 <a name="resources06"></a><li id="resources06">android.os.Build reference: <a href="http://developer.android.com/reference/android/os/Build.html">http://developer.android.com/reference/android/os/Build.html</a></li>
 <a name="resources07"></a><li id="resources07">Android 4.4 allowed version strings: <a href="http://source.android.com/compatibility/4.4/versions.html">http://source.android.com/compatibility/4.4/versions.html</a></li>
 <a name="resources08"></a><li id="resources08">Renderscript: <a href="http://developer.android.com/guide/topics/graphics/renderscript.html">http://developer.android.com/guide/topics/graphics/renderscript.html</a></li>
 <a name="resources09"></a><li id="resources09">Hardware Acceleration: <a href="http://developer.android.com/guide/topics/graphics/hardware-accel.html">http://developer.android.com/guide/topics/graphics/hardware-accel.html</a></li>
 <a name="resources10"></a><li id="resources10">android.webkit.WebView class: <a href="http://developer.android.com/reference/android/webkit/WebView.html">http://developer.android.com/reference/android/webkit/WebView.html</a></li>
 <a name="resources11"></a><li id="resources11">HTML5: <a href="http://www.whatwg.org/specs/web-apps/current-work/multipage/">http://www.whatwg.org/specs/web-apps/current-work/multipage/</a></li>
 <a name="resources12"></a><li id="resources12">HTML5 offline capabilities: <a href="http://dev.w3.org/html5/spec/Overview.html#offline">http://dev.w3.org/html5/spec/Overview.html#offline</a></li>
 <a name="resources13"></a><li id="resources13">HTML5 video tag: <a href="http://dev.w3.org/html5/spec/Overview.html#video">http://dev.w3.org/html5/spec/Overview.html#video</a></li>
 <a name="resources14"></a><li id="resources14">HTML5/W3C geolocation API: <a href="http://www.w3.org/TR/geolocation-API/">http://www.w3.org/TR/geolocation-API/</a></li>
 <a name="resources15"></a><li id="resources15">HTML5/W3C webstorage API: <a href="http://www.w3.org/TR/webstorage/">http://www.w3.org/TR/webstorage/</a></li>
 <a name="resources16"></a><li id="resources16">HTML5/W3C IndexedDB API: <a href="http://www.w3.org/TR/IndexedDB/">http://www.w3.org/TR/IndexedDB/</a></li>
 <a name="resources17"></a><li id="resources17">Dalvik Virtual Machine specification: available in the Android source code, at dalvik/docs</li>
 <a name="resources18"></a><li id="resources18">AppWidgets: <a href="http://developer.android.com/guide/practices/ui_guidelines/widget_design.html">http://developer.android.com/guide/practices/ui_guidelines/widget_design.html</a></li>
 <a name="resources19"></a><li id="resources19">Notifications: <a href="http://developer.android.com/guide/topics/ui/notifiers/notifications.html">http://developer.android.com/guide/topics/ui/notifiers/notifications.html</a></li>
 <a name="resources20"></a><li id="resources20">Application Resources: <a href="http://code.google.com/android/reference/available-resources.html">http://code.google.com/android/reference/available-resources.html</a></li>
 <a name="resources21"></a><li id="resources21">Status Bar icon style guide: <a href="http://developer.android.com/guide/practices/ui_guidelines/icon_design_status_bar.html">http://developer.android.com/guide/practices/ui_guidelines/icon_design_status_bar.html</a></li>
 <a name="resources22"></a><li id="resources22">Search Manager: <a href="http://developer.android.com/reference/android/app/SearchManager.html">http://developer.android.com/reference/android/app/SearchManager.html</a></li>
 <a name="resources23"></a><li id="resources23">Toasts: <a href="http://developer.android.com/reference/android/widget/Toast.html">http://developer.android.com/reference/android/widget/Toast.html</a></li>
 <a name="resources24"></a><li id="resources24">Themes: <a href="http://developer.android.com/guide/topics/ui/themes.html">http://developer.android.com/guide/topics/ui/themes.html</a></li>
 <a name="resources25"></a><li id="resources25">R.style class: <a href="http://developer.android.com/reference/android/R.style.html">http://developer.android.com/reference/android/R.style.html</a></li>
 <a name="resources26"></a><li id="resources26">Live Wallpapers: <a href="http://developer.android.com/resources/articles/live-wallpapers.html">http://developer.android.com/resources/articles/live-wallpapers.html</a></li>
 <a name="resources27"></a><li id="resources27">Android Device Administration: <a href="http://developer.android.com/guide/topics/admin/device-admin.html">http://developer.android.com/guide/topics/admin/device-admin.html</a></li>
 <a name="resources28"></a><li id="resources28">DevicePolicyManager reference: <a href="http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html">http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html</a></li>
 <a name="resources29"></a><li id="resources29">Android Accessibility Service APIs: <a href="http://developer.android.com/reference/android/accessibilityservice/package-summary.html">http://developer.android.com/reference/android/accessibilityservice/package-summary.html</a></li>
 <a name="resources30"></a><li id="resources30">Android Accessibility APIs: <a href="http://developer.android.com/reference/android/view/accessibility/package-summary.html">http://developer.android.com/reference/android/view/accessibility/package-summary.html</a></li>
 <a name="resources31"></a><li id="resources31">Eyes Free project: <a href="http://http://code.google.com/p/eyes-free">http://code.google.com/p/eyes-free</a></li>
 <a name="resources32"></a><li id="resources32">Text-To-Speech APIs: <a href="http://developer.android.com/reference/android/speech/tts/package-summary.html">http://developer.android.com/reference/android/speech/tts/package-summary.html</a></li>
 <a name="resources33"></a><li id="resources33">Reference tool documentation (for adb, aapt, ddms, systrace): <a href="http://developer.android.com/guide/developing/tools/index.html">http://developer.android.com/guide/developing/tools/index.html</a></li>
 <a name="resources34"></a><li id="resources34">Android apk file description: <a href="http://developer.android.com/guide/topics/fundamentals.html">http://developer.android.com/guide/topics/fundamentals.html</a></li>
 <a name="resources35"></a><li id="resources35">Manifest files: <a href="http://developer.android.com/guide/topics/manifest/manifest-intro.html">http://developer.android.com/guide/topics/manifest/manifest-intro.html</a></li>
 <a name="resources36"></a><li id="resources36">Monkey testing tool: <a href="http://developer.android.com/guide/developing/tools/monkey.html">http://developer.android.com/guide/developing/tools/monkey.html</a></li>
 <a name="resources37"></a><li id="resources37">Android android.content.pm.PackageManager class and Hardware Features List: <a href="http://developer.android.com/reference/android/content/pm/PackageManager.html">http://developer.android.com/reference/android/content/pm/PackageManager.html</a></li>
 <a name="resources38"></a><li id="resources38">Supporting Multiple Screens: <a href="http://developer.android.com/guide/practices/screens_support.html">http://developer.android.com/guide/practices/screens_support.html</a></li>
 <a name="resources39"></a><li id="resources39">android.util.DisplayMetrics: <a href="http://developer.android.com/reference/android/util/DisplayMetrics.html">http://developer.android.com/reference/android/util/DisplayMetrics.html</a></li>
 <a name="resources40"></a><li id="resources40">android.content.res.Configuration: <a href="http://developer.android.com/reference/android/content/res/Configuration.html">http://developer.android.com/reference/android/content/res/Configuration.html</a></li>
 <a name="resources41"></a><li id="resources41">android.hardware.SensorEvent: <a href="http://developer.android.com/reference/android/hardware/SensorEvent.html">http://developer.android.com/reference/android/hardware/SensorEvent.html</a></li>
 <a name="resources42"></a><li id="resources42">Bluetooth API: <a href="http://developer.android.com/reference/android/bluetooth/package-summary.html">http://developer.android.com/reference/android/bluetooth/package-summary.html</a></li>
 <a name="resources43"></a><li id="resources43">NDEF Push Protocol: <a href="http://source.android.com/compatibility/ndef-push-protocol.pdf">http://source.android.com/compatibility/ndef-push-protocol.pdf</a></li>
 <a name="resources44"></a><li id="resources44">MIFARE MF1S503X: <a href="http://www.nxp.com/documents/data_sheet/MF1S503x.pdf">http://www.nxp.com/documents/data_sheet/MF1S503x.pdf</a></li>
 <a name="resources45"></a><li id="resources45">MIFARE MF1S703X: <a href="http://www.nxp.com/documents/data_sheet/MF1S703x.pdf">http://www.nxp.com/documents/data_sheet/MF1S703x.pdf</a></li>
 <a name="resources46"></a><li id="resources46">MIFARE MF0ICU1: <a href="http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf">http://www.nxp.com/documents/data_sheet/MF0ICU1.pdf</a></li>
 <a name="resources47"></a><li id="resources47">MIFARE MF0ICU2: <a href="http://www.nxp.com/documents/short_data_sheet/MF0ICU2_SDS.pdf">http://www.nxp.com/documents/short_data_sheet/MF0ICU2_SDS.pdf</a></li>
 <a name="resources48"></a><li id="resources48">MIFARE AN130511: <a href="http://www.nxp.com/documents/application_note/AN130511.pdf">http://www.nxp.com/documents/application_note/AN130511.pdf</a></li>
 <a name="resources49"></a><li id="resources49">MIFARE AN130411: <a href="http://www.nxp.com/documents/application_note/AN130411.pdf">http://www.nxp.com/documents/application_note/AN130411.pdf</a></li>
 <a name="resources50"></a><li id="resources50">Camera orientation API: <a href="http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)">http://developer.android.com/reference/android/hardware/Camera.html#setDisplayOrientation(int)</a></li>
 <a name="resources51"></a><li id="resources51">Camera: <a href="http://developer.android.com/reference/android/hardware/Camera.html">http://developer.android.com/reference/android/hardware/Camera.html</a></li>
 <a name="resources52"></a><li id="resources52">Android Open Accessories: <a href="http://developer.android.com/guide/topics/usb/accessory.html">http://developer.android.com/guide/topics/usb/accessory.html</a></li>
 <a name="resources53"></a><li id="resources53">USB Host API: <a href="http://developer.android.com/guide/topics/usb/host.html">http://developer.android.com/guide/topics/usb/host.html</a></li>
 <a name="resources54"></a><li id="resources54">Android Security and Permissions reference: <a href="http://developer.android.com/guide/topics/security/permissions.html">http://developer.android.com/guide/topics/security/permissions.html</a></li>
 <a name="resources55"></a><li id="resources55">Apps for Android: <a href="http://code.google.com/p/apps-for-android">http://code.google.com/p/apps-for-android</a></li>
 <a name="resources56"></a><li id="resources56">Android DownloadManager: <a href="http://developer.android.com/reference/android/app/DownloadManager.html">http://developer.android.com/reference/android/app/DownloadManager.html</a></li>
 <a name="resources57"></a><li id="resources57">Android File Transfer: <a href="http://www.android.com/filetransfer">http://www.android.com/filetransfer</a></li>
 <a name="resources58"></a><li id="resources58">Android Media Formats: <a href="http://developer.android.com/guide/appendix/media-formats.html">http://developer.android.com/guide/appendix/media-formats.html</a></li>
 <a name="resources59"></a><li id="resources59">HTTP Live Streaming Draft Protocol: <a href="http://tools.ietf.org/html/draft-pantos-http-live-streaming-03">http://tools.ietf.org/html/draft-pantos-http-live-streaming-03</a></li>
 <a name="resources60"></a><li id="resources60">NFC Connection Handover: <a href="http://www.nfc-forum.org/specs/spec_list/#conn_handover/">http://www.nfc-forum.org/specs/spec_list/#conn_handover</a></li>
 <a name="resources61"></a><li id="resources61">Bluetooth Secure Simple Pairing Using NFC: <a href="http://www.nfc-forum.org/resources/AppDocs/NFCForum_AD_BTSSP_1_0.pdf">http://www.nfc-forum.org/resources/AppDocs/NFCForum_AD_BTSSP_1_0.pdf</a></li>
 <a name="resources62"></a>
 <li id="resources62">Wi-Fi Multicast API: <a href="http://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock.html">http://developer.android.com/reference/android/net/wifi/WifiManager.MulticastLock.html</a></li>
 <a name="resources63"></a><li id="resources63">Action Assist: <a href="http://developer.android.com/reference/android/content/Intent.html#ACTION_ASSIST">http://developer.android.com/reference/android/content/Intent.html#ACTION_ASSIST</a></li>
 <a name="resources64"></a><li id="resources64">USB Charging Specification: <a href="http://www.usb.org/developers/devclass_docs/USB_Battery_Charging_1.2.pdf">http://www.usb.org/developers/devclass_docs/USB_Battery_Charging_1.2.pdf</a></li>
 <a name="resources65"></a><li id="resources65">Android Beam: <a href="http://developer.android.com/guide/topics/nfc/nfc.html">http://developer.android.com/guide/topics/nfc/nfc.html</a></li>
 <a name="resources66"></a><li id="resources66">Android USB Audio: <a href="http://developer.android.com/reference/android/hardware/usb/UsbConstants.html#USB_CLASS_AUDIO">http://developer.android.com/reference/android/hardware/usb/UsbConstants.html#USB_CLASS_AUDIO</a></li>
 <a name="resources67"></a><li id="resources67">Android NFC Sharing Settings: <a href="http://developer.android.com/reference/android/provider/Settings.html#ACTION_NFCSHARING_SETTINGS">http://developer.android.com/reference/android/provider/Settings.html#ACTION_NFCSHARING_SETTINGS</a></li>
 <a name="resources68"></a>
 <li id="resources68">Wi-Fi Direct (Wi-Fi P2P): <a href="http://developer.android.com/reference/android/net/wifi/p2p/WifiP2pManager.html">http://developer.android.com/reference/android/net/wifi/p2p/WifiP2pManager.html</a></li>
 <a name="resources69"></a><li id="resources69">Lock and Home Screen Widget: <a href="http://developer.android.com/reference/android/appwidget/AppWidgetProviderInfo.html">http://developer.android.com/reference/android/appwidget/AppWidgetProviderInfo.html</a></li>
 <a name="resources70"></a><li id="resources70">UserManager reference: <a href="http://developer.android.com/reference/android/os/UserManager.html">http://developer.android.com/reference/android/os/UserManager.html</a></li>
 <a name="resources71"></a><li id="resources71">External Storage reference: <a
 href="http://source.android.com/devices/tech/storage">http://source.android.com/devices/tech/storage</a></li>
 <a name="resources72"></a><li id="resources72">External Storage APIs: <a href="http://developer.android.com/reference/android/os/Environment.html">http://developer.android.com/reference/android/os/Environment.html</a></li>
 <a name="resources73"></a><li id="resources73">SMS Short Code: <a href="http://en.wikipedia.org/wiki/Short_code">http://en.wikipedia.org/wiki/Short_code</a></li>
 <a name="resources74"></a><li id="resources74">Media Remote Control Client: <a href="http://developer.android.com/reference/android/media/RemoteControlClient.html">http://developer.android.com/reference/android/media/RemoteControlClient.html</a></li>
 <a name="resources75"></a><li id="resources75">Display Manager: <a href="http://developer.android.com/reference/android/hardware/display/DisplayManager.html">http://developer.android.com/reference/android/hardware/display/DisplayManager.html</a></li>
 <a name="resources76"></a><li id="resources76">Dreams: <a href="http://developer.android.com/reference/android/service/dreams/DreamService.html">http://developer.android.com/reference/android/service/dreams/DreamService.html</a></li>
 <a name="resources77"></a><li id="resources77">Android Application Development-Related Settings: <a href="http://developer.android.com/reference/android/provider/Settings.html#ACTION_APPLICATION_DEVELOPMENT_SETTINGS">http://developer.android.com/reference/android/provider/Settings.html#ACTION_APPLICATION_DEVELOPMENT_SETTINGS</a></li>
 <a name="resources78"></a><li id="resources78">Camera: <a href="http://developer.android.com/reference/android/hardware/Camera.Parameters.html">http://developer.android.com/reference/android/hardware/Camera.Parameters.html</a></li>
 <a name="resources79"></a><li id="resources79">EGL Extension-EGL_ANDROID_RECORDABLE: <a href="http://www.khronos.org/registry/egl/extensions/ANDROID/EGL_ANDROID_recordable.txt">http://www.khronos.org/registry/egl/extensions/ANDROID/EGL_ANDROID_recordable.txt</a></li>
 <a name="resources80"></a><li id="resources80">Motion Event API: <a href="http://developer.android.com/reference/android/view/MotionEvent.html">http://developer.android.com/reference/android/view/MotionEvent.html</a></li>
 <a name="resources81"></a><li id="resources81">Touch Input Configuration: <a href="http://source.android.com/devices/tech/input/touch-devices.html">http://source.android.com/devices/tech/input/touch-devices.html</a></li>
 <a name="resources82"></a><li id="resources82">Unicode 6.1.0: <a href="http://www.unicode.org/versions/Unicode6.1.0/">http://www.unicode.org/versions/Unicode6.1.0/</a></li>
 <a name="resources83"></a><li id="resources83">WebView compatibility: <a href="http://www.chromium.org/">http://www.chromium.org/</a></li>
 <a name="resources84"></a><li id="resources84">Android Device Owner App: <a href="http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#isDeviceOwnerApp(java.lang.String)">http://developer.android.com/reference/android/app/admin/DevicePolicyManager.html#isDeviceOwnerApp(java.lang.String)</a></li>
 <a name="resources85"></a><li id="resources85">WifiManager API: <a href="http://developer.android.com/reference/android/net/wifi/WifiManager.html">http://developer.android.com/reference/android/net/wifi/WifiManager.html</a></li>
 <a name="resources86"></a><li id="resources86">RTC Hardware Coding Requirements: <a href="http://www.webmproject.org/hardware/rtc-coding-requirements/">http://www.webmproject.org/hardware/rtc-coding-requirements/</a></li>
 <a name="resources87"></a><li id="resources87">Settings.Secure LOCATION_MODE: <a
 href="http://developer.android.com/reference/android/provider/Settings.Secure.html#LOCATION_MODE">http://developer.android.com/reference/android/provider/Settings.Secure.html#LOCATION_MODE</a></li>
 <a name="resources88"></a><li id="resources88">Content Resolver: <a href="http://developer.android.com/reference/android/content/ContentResolver.html">http://developer.android.com/reference/android/content/ContentResolver.html</a></li>
 <a name="resources89"></a><li id="resources89">SettingInjectorService: <a
 href="http://developer.android.com/reference/android/location/SettingInjectorService.html">http://developer.android.com/reference/android/location/SettingInjectorService.html</a></li>
 <a name="resources90"></a><li id="resources90">Host-based Card Emulation: <a href="http://developer.android.com/guide/topics/connectivity/nfc/hce.html">http://developer.android.com/guide/topics/connectivity/nfc/hce.html</a></li>
 <a name="resources91"></a><li id="resources91">Telephony Provider: <a href="http://developer.android.com/reference/android/provider/Telephony.html">http://developer.android.com/reference/android/provider/Telephony.html</a></li>
 </ol>
 <p>Many of these resources are derived directly or indirectly from the Android
 SDK, and will be functionally identical to the information in that SDK's
 documentation. In any cases where this Compatibility Definition or the
 Compatibility Test Suite disagrees with the SDK documentation, the SDK
 documentation is considered authoritative. Any technical details provided in
 the references included above are considered by inclusion to be part of this
 Compatibility Definition.</p>

 <a name="section-3"></a><h2 id="section-3">3. Software</h2>
 <a name="section-3.1"></a><h3 id="section-3.1">3.1. Managed API Compatibility</h3>
 <p>The managed (Dalvik-based) execution environment is the primary vehicle for
 Android applications. The Android application programming interface (API) is
 the set of Android platform interfaces exposed to applications running in the
 managed VM environment. Device implementations MUST provide complete
 implementations, including all documented behaviors, of any documented API
 exposed by the Android SDK [<a href="#resources04">Resources, 4</a>].</p>
 <p>Device implementations MUST NOT omit any managed APIs, alter API interfaces
 or signatures, deviate from the documented behavior, or include no-ops, except
 where specifically allowed by this Compatibility Definition.</p>
 <p>This Compatibility Definition permits some types of hardware for which
 Android includes APIs to be omitted by device implementations. In such cases,
 the APIs MUST still be present and behave in a reasonable way. See
 <a href="#section-7">Section 7</a> for specific requirements for this scenario.
 </p>

 <a name="section-3.2"></a><h3 id="section-3.2">3.2. Soft API Compatibility</h3>
 <p>In addition to the managed APIs from Section 3.1, Android also includes a
 significant runtime-only "soft" API, in the form of such things such as
 Intents, permissions, and similar aspects of Android applications that cannot
 be enforced at application compile time.</p>
 <a name="section-3.2.1"></a><h4 id="section-3.2.1">3.2.1. Permissions</h4>
 <p>Device implementers MUST support and enforce all permission constants as
 documented by the Permission reference page [<a
 href="#resources05">Resources, 5</a>]. Note that Section 9 lists additional
 requirements related to the Android security model.</p>
 <a name="section-3.2.2"></a><h4 id="section-3.2.2">3.2.2. Build Parameters</h4>
 <p>The Android APIs include a number of constants on the <code>android.os.Build</code>
 class [<a href="#resources06">Resources, 6</a>] that are intended to describe
 the current device. To provide consistent, meaningful values across device
 implementations, the table below includes additional restrictions on the
 formats of these values to which device implementations MUST conform.</p>
 <table>
 <tbody>
 <tr>
 <td><b>Parameter</b></td>
 <td><b>Comments</b></td>
 </tr>
 <tr>
 <td>VERSION.RELEASE</td>
 <td>The version of the currently-executing Android system, in human-readable
 format. This field MUST have one of the string values defined in [<a
 href="#resources07">Resources, 7</a>].</td>
 </tr>
 <tr>
 <td>VERSION.SDK</td>
 <td>The version of the currently-executing Android system, in a format
 accessible to third-party application code. For Android 4.4, this
 field MUST have the integer value 19.</td>
 </tr>
 <tr>
 <td>VERSION.SDK_INT</td>
 <td>The version of the currently-executing Android system, in a format
 accessible to third-party application code. For Android 4.4, this
 field MUST have the integer value 19.</td>
 </tr>
 <tr>
 <td>VERSION.INCREMENTAL</td>
 <td>A value chosen by the device implementer designating the specific build of
 the currently-executing Android system, in human-readable format. This value
 MUST NOT be re-used for different builds made available to end users. A typical use
 of this field is to indicate which build number or source-control change
 identifier was used to generate the build. There are no requirements on the
 specific format of this field, except that it MUST NOT be null or the empty
 string ("").</td>
 </tr>
 <tr>
 <td>BOARD</td>
 <td>A value chosen by the device implementer identifying the specific internal
 hardware used by the device, in human-readable format. A possible use of this
 field is to indicate the specific revision of the board powering the device.
 The value of this field MUST be encodable as 7-bit ASCII and match the regular expression
 <code>"^[a-zA-Z0-9.,_-]+$"</code>.</td>
 </tr>
 <tr>
 <td>BRAND</td>
 <td>A value reflecting the brand name associated with the device as
 known to the end users. MUST be in human-readable format and SHOULD represent
 the manufacturer of the device or the company brand under which the device is
 marketed. The value of this field MUST be encodable as 7-bit ASCII and match the
 regular expression <code>"^[a-zA-Z0-9.,_-]+$"</code>.
 </td>
 </tr>
 <tr>
 <td>CPU_ABI</td>
 <td>The name of the instruction set (CPU type + ABI convention) of native code.
 See <a href="#section-3.3">Section 3.3: Native API Compatibility</a>.
 </td>
 </tr>
 <tr>
 <td>CPU_ABI2</td>
 <td>The name of the second instruction set (CPU type + ABI convention) of native code.
 See <a href="#section-3.3">Section 3.3: Native API Compatibility</a>.
 </td>
 </tr>
 <tr>
 <td>DEVICE</td>
 <td>A value chosen by the device implementer containing the development name or
 code name identifying the configuration of the hardware features and industrial
 design of the device. The value of this field MUST be encodable as 7-bit ASCII
 and match the regular expression <code>"^[a-zA-Z0-9.,_-]+$"</code>.
 </td>
 </tr>
 <tr>
 <td>FINGERPRINT</td>
 <td>A string that uniquely identifies this build. It SHOULD be reasonably
 human-readable. It MUST follow this template:
 <br/><code>$(BRAND)/$(PRODUCT)/$(DEVICE):$(VERSION.RELEASE)/$(ID)/$(VERSION.INCREMENTAL):$(TYPE)/$(TAGS)</code><br/>
 For example:
 <br/><code>acme/myproduct/mydevice:4.4/KRT16/3359:userdebug/test-keys</code><br/>
 The fingerprint MUST NOT include whitespace characters. If other fields included in the
 template above have whitespace characters, they MUST be replaced in the build
 fingerprint with another character, such as the underscore ("_") character.
 The value of this field MUST be encodable as 7-bit ASCII.</td>
 </tr>
 <tr>
 <td>HARDWARE</td>
 <td>The name of the hardware (from the kernel command line or /proc).  It SHOULD be
 reasonably human-readable. The value of this field MUST be encodable as 7-bit ASCII and
 match the regular expression <code>"^[a-zA-Z0-9.,_-]+$"</code>.</td>
 </tr>
 <tr>
 <td>HOST</td>
 <td>A string that uniquely identifies the host the build was built on, in
 human readable format. There are no requirements on the specific format of
 this field, except that it MUST NOT be null or the empty string ("").</td>
 </tr>
 <tr>
 <td>ID</td>
 <td>An identifier chosen by the device implementer to refer to a specific
 release, in human readable format. This field can be the same as
 android.os.Build.VERSION.INCREMENTAL, but SHOULD be a value sufficiently
 meaningful for end users to distinguish between software builds. The value of
 this field MUST be encodable as 7-bit ASCII and match the regular expression
 <code>"^[a-zA-Z0-9.,_-]+$"</code>.
 </td>
 </tr>
 <tr>
 <td>MANUFACTURER</td>
 <td>The trade name of the Original Equipment Manufacturer (OEM) of the product.
 There are no requirements on the specific format of this field, except that it
 MUST NOT be null or the empty string ("").</td>
 </tr>
 <tr>
 <td>MODEL</td>
 <td>A value chosen by the device implementer containing the name of the device
 as known to the end user. This SHOULD be the same name under which the device
 is marketed and sold to end users. There are no requirements on the specific
 format of this field, except that it MUST NOT be null or the empty string
 ("").</td>
 </tr>
 <tr>
 <td>PRODUCT</td>
 <td>A value chosen by the device implementer containing the development name or
 code name of the specific product (SKU) that SHOULD be unique within the same
 brand. MUST be human-readable, but is not necessarily intended for view by end
 users. The value of this field MUST be encodable as 7-bit ASCII and match the
 regular expression <code>"^[a-zA-Z0-9.,_-]+$"</code>.
 </td>
 </tr>
 <tr>
 <td>SERIAL</td>
 <td>A hardware serial number, which MUST be available. The value of this field MUST be encodable
 as 7-bit ASCII and match the regular expression
 <code>"^([a-zA-Z0-9]{6,20})$"</code>.</td>
 </tr>
 <tr>
 <td>TAGS</td>
 <td>A comma-separated list of tags chosen by the device implementer that
 further distinguishes the build. For example, "unsigned,debug". The value of
 this field MUST be encodable as 7-bit ASCII and match the regular expression
 <code>"^[a-zA-Z0-9.,_-]+$"</code>.</td>
 </tr>
 <tr>
 <td>TIME</td>
 <td>A value representing the timestamp of when the build occurred.</td>
 </tr>
 <tr>
 <td>TYPE</td>
 <td>A value chosen by the device implementer specifying the runtime
 configuration of the build. This field SHOULD have one of the values
 corresponding to the three typical Android runtime configurations: "user",
 "userdebug", or "eng". The value of this field MUST be
 encodable as 7-bit ASCII and match the regular expression
 <code>"^[a-zA-Z0-9.,_-]+$"</code>.</td>
 </tr>
 <tr>
 <td>USER</td>
 <td>A name or user ID of the user (or automated user) that generated the
 build. There are no requirements on the specific format of this field, except
 that it MUST NOT be null or the empty string ("").</td>
 </tr>
 </tbody>
 </table>
 <a name="section-3.2.3"></a><h4 id="section-3.2.3">3.2.3. Intent Compatibility</h4>
 <p>
 Device implementations MUST honor Android's loose-coupling Intent system, as
 described in the sections below. By "honored", it is meant that the device
 implementer MUST provide an Android Activity or Service that specifies a
 matching Intent filter and binds to and implements correct behavior for each
 specified Intent pattern.</p>
 <a name="section-3.2.3.1"></a><h4 id="section-3.2.3.1">3.2.3.1. Core Application Intents</h4>
 <p>The Android upstream project defines a number of core applications, such as
 contacts, calendar, photo gallery, music player, and so on. Device implementers
 MAY replace these applications with alternative versions.</p>
 <p>However, any such alternative versions MUST honor the same Intent patterns
 provided by the upstream project. For example, if a device contains an
 alternative music player, it must still honor the Intent pattern issued by
 third-party applications to pick a song.</p>
 <p>The following applications are considered core Android system
 applications:</p>
 <ul>
 <li>Desk Clock</li>
 <li>Browser</li>
 <li>Calendar</li>
 <li>Contacts</li>
 <!--<li>Email</li>-->
 <li>Gallery</li>
 <li>GlobalSearch</li>
 <li>Launcher</li>
 <!-- <li>LivePicker (that is, the Live Wallpaper picker application; MAY be omitted
 if the device does not support Live Wallpapers, per Section 3.8.5.)</li> -->
 <!-- <li>Messaging (AKA "Mms")</li> -->
 <li>Music</li>
 <!-- <li>Phone</li> -->
 <li>Settings</li>
 <!-- <li>SoundRecorder</li> -->
 </ul>
 <p>The core Android system applications include various Activity, or Service
 components that are considered "public".  That is, the attribute
 "android:exported" may be absent, or may have the value "true".</p>
 <p>For every Activity or Service defined
 in one of the core Android system apps that is not marked as non-public via an
 android:exported attribute with the value "false", device implementations MUST
 include a component of the same type implementing the same Intent filter
 patterns as the core Android system app.</p>
 <p>In other words, a device implementation MAY replace core Android system
 apps; however, if it does, the device implementation MUST support all Intent
 patterns defined by each core Android system app being replaced.</p>
 <a name="section-3.2.3.2"></a><h4 id="section-3.2.3.2">3.2.3.2. Intent Overrides</h4>
 <p>As Android is an extensible platform, device implementations MUST allow each
 Intent pattern referenced in Section 3.2.3.1 to be overridden by third-party
 applications. The upstream Android open source implementation allows this by
 default; device implementers MUST NOT attach special privileges to system
 applications' use of these Intent patterns, or prevent third-party
 applications from binding to and assuming control of these patterns. This
 prohibition specifically includes but is not limited to disabling the
 "Chooser" user interface that allows the user to select between multiple
 applications which all handle the same Intent pattern.</p>
 <p>However, device implementations MAY provide default activities for specific
 URI patterns (eg. http://play.google.com) if the default activity provides a
 more specific filter for the data URI. For example, an intent filter specifying
 the data URI "http://www.android.com" is more specific than the browser filter
 for "http://". Device implementations MUST provide a user interface for users
 to modify the default activity for intents.</p>

 <a name="section-3.2.3.3"></a><h4 id="section-3.2.3.3">3.2.3.3. Intent Namespaces</h4>
 <p>Device implementations MUST NOT include any Android component that honors any
 new Intent or Broadcast Intent patterns using an ACTION, CATEGORY, or other
 key string in the android.* or com.android.* namespace. Device implementers
 MUST NOT include any Android components that honor any new Intent or Broadcast
 Intent patterns using an ACTION, CATEGORY, or other key string in a package
 space belonging to another organization. Device implementers MUST NOT alter or
 extend any of the Intent patterns used by the core apps listed in Section
 3.2.3.1. Device implementations MAY include Intent patterns using
 namespaces clearly and obviously associated with their own organization.</p>
 <p>This prohibition is analogous to that specified for Java language classes
 in Section 3.6.</p>

 <a name="section-3.2.3.4"></a><h4 id="section-3.2.3.4">3.2.3.4. Broadcast Intents</h4>
 <p>Third-party applications rely on the platform to broadcast certain Intents
 to notify them of changes in the hardware or software environment.
 Android-compatible devices MUST broadcast the public broadcast Intents in
 response to appropriate system events. Broadcast Intents are described in the
 SDK documentation.</p>

 <a name="section-3.2.3.5"></a><h4 id="section-3.2.3.5">3.2.3.5. Default App Settings</h4>
 <p>Android 4.4 adds settings that allow users to select their default Home and
 SMS applications. Device implementations MUST provide a similar user settings
 menu for each, compatible with the Intent filter pattern and API methods
 described in the SDK documentation [<a href="#resources91">Resources, 91</a>].
 </p>

 <a name="section-3.3"></a><h3 id="section-3.3">3.3. Native API Compatibility</h3>
 <a name="section-3.3.1"></a><h4 id="section-3.3.1">3.3.1 Application Binary Interfaces</h4>
 <p>Managed code running in Dalvik can call into native code provided in the
 application .apk file as an ELF .so file compiled for the appropriate device
 hardware architecture. As native code is highly dependent on the underlying
 processor technology, Android defines a number of Application Binary
 Interfaces (ABIs) in the Android NDK, in the file
 <code>docs/CPU-ARCH-ABIS.html</code>. If a device implementation is compatible
 with one or more defined ABIs, it SHOULD implement compatibility with the
 Android NDK, as below.</p>
 <p>If a device implementation includes support for an Android ABI, it:</p>
 <ul>
 <li>MUST include support for code running in the managed environment to call
 into native code, using the standard Java Native Interface (JNI)
 semantics</li>
 <li>MUST be source-compatible (i.e. header compatible) and binary-compatible
 (for the ABI) with each required library in the list below</li>
 <li>MUST accurately report the native Application Binary Interface (ABI)
 supported by the device, via the <code>android.os.Build.CPU_ABI</code>
 API and <code>android.os.Build.CPU_ABI2</code> parameters.</li>
 <li>MUST report, via <code>android.os.Build.CPU_ABI2</code>, only those ABIs
 documented in the latest version of the Android NDK, in the file
 <code>docs/CPU-ARCH-ABIS.html</code></li>
 <li>MUST report, via <code>android.os.Build.CPU_ABI</code>, only one of the
 ABIs listed below</li>
   <ul>
   <li>armeabi-v7a</li>
   <li>x86</li>
   <li>mips</li>
   </ul>
 <li>SHOULD be built using the source code and header files available in the
 upstream Android Open Source Project</li>
 </ul>
 <p>The following native code APIs MUST be available to apps that include
 native code:</p>
 <ul>
 <li>libc (C library)</li>
 <li>libm (math library)</li>
 <li>Minimal support for C++</li>
 <li>JNI interface</li>
 <li>liblog (Android logging)</li>
 <li>libz (Zlib compression)</li>
 <li>libdl (dynamic linker)</li>
 <li>libGLESv1_CM.so (OpenGL ES 1.0)</li>
 <li>libGLESv2.so (OpenGL ES 2.0)</li>
 <li>libGLESv3.so (OpenGL ES 3.0)</li>
 <li>libEGL.so (native OpenGL surface management)</li>
 <li>libjnigraphics.so</li>
 <li>libOpenSLES.so (OpenSL ES 1.0.1 audio support)</li>
 <li>libOpenMAXAL.so (OpenMAX AL 1.0.1 support)</li>
 <li>libandroid.so (native Android activity support)</li>
 <li>Support for OpenGL, as described below</li>
 </ul>
 <p>Note that future releases of the Android NDK may introduce support for
 additional ABIs. If a device implementation is not compatible with an existing
 predefined ABI, it MUST NOT report support for any ABI at all.</p>
 <p>Note that device implementations MUST include libGLESv3.so and it MUST symlink (symbolic)
 link to libGLESv2.so. On device implementations that declare support for OpenGL ES 3.0, libGLESv2.so
 MUST export the OpenGL ES 3.0 function symbols in addition to the OpenGL ES 2.0 function symbols.</p>
 <p>Native code compatibility is challenging. For this reason, it should be
 repeated that device implementers are VERY strongly encouraged to use the
 upstream implementations of the libraries listed above to help ensure
 compatibility.</p>

 <a name="section-3.4"></a><h3 id="section-3.4">3.4. Web Compatibility</h3>
 <a name="section-3.4.1"></a><h4 id="section-3.4.1">3.4.1. WebView Compatibility</h4>
 <p>The Android Open Source implementation uses code from the Chromium
 Project to implement the <code>android.webkit.WebView</code> [<a href="#resources10">Resources, 10</a>] . Because it is not feasible
 to develop a comprehensive test suite for a web rendering system, device
 implementers MUST use the specific upstream build of Chromium in the WebView
 implementation. Specifically:</p>
 <ul>
 <li>Device <code>android.webkit.WebView</code> implementations MUST be based
 on the Chromium build from the upstream Android Open Source Project for Android 4.4.
 This build includes a specific set of functionality and security fixes for the
 WebView. [<a href="#resources83">Resources, 83</a>]</li>
 <li>The user agent string reported by the WebView MUST be in this format:<br/>
     <code>Mozilla/5.0 (Linux; Android $(VERSION); $(LOCALE); $(MODEL)
 Build/$(BUILD)) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0
 $(CHROMIUM_VER) Mobile Safari/537.36</code>
   <ul>
   <li>The value of the $(VERSION) string MUST be the same as the value for
 <code>android.os.Build.VERSION.RELEASE</code>.</li>
   <li>The value of the $(LOCALE) string is optional, SHOULD follow the ISO
 conventions for country code and language, and SHOULD refer to the current
 configured locale of the device. If omitted, the trailing semicolon MUST
 also be removed.</li>
   <li>The value of the $(MODEL) string MUST be the same as the value for
 <code>android.os.Build.MODEL</code>.</li>
   <li>The value of the $(BUILD) string MUST be the same as the value for
 <code>android.os.Build.ID</code>.</li>
   <li>The value of the $(CHROMIUM_VER) string MUST be the version of Chromium in
 the upstream Android Open Source Project.</li>
   <li>Device implementations MAY omit <code>Mobile</code> in the user agent
 string.</li>
   </ul>
 </li>
 </ul>
 <p>The WebView component SHOULD include support for as much of HTML5 [<a
 href="#resources11">Resources, 11</a>] as possible.</p>
 <a name="section-3.4.2"></a><h4 id="section-3.4.2">3.4.2. Browser Compatibility</h4>
 <p>Device implementations MUST include a standalone Browser application for
 general user web browsing. The standalone Browser MAY be based on a
 browser technology other than WebKit. However, even if an alternate Browser
 application is used, the <code>android.webkit.WebView</code> component
 provided to third-party applications MUST be based on WebKit, as described in
 Section 3.4.1.</p>
 <p>Implementations MAY ship a custom user agent string in the standalone
 Browser application.</p>
 <p>The standalone Browser application (whether based on the upstream
 WebKit Browser application or a third-party replacement) SHOULD include support
 for as much of HTML5 [<a href="#resources11">Resources, 11</a>] as possible.
 Minimally, device implementations MUST support each of these APIs associated
 with HTML5:</p>
 <ul>
 <li>application cache/offline operation [<a href="#resources12">Resources, 12</a>]</li>
 <li>the &lt;video&gt; tag [<a href="#resources13">Resources, 13</a>]</li>
 <li>geolocation [<a href="#resources14">Resources, 14</a>]</li>
 </ul>
 <p>Additionally, device implementations MUST support the HTML5/W3C webstorage
 API [<a href="#resources15">Resources, 15</a>], and SHOULD support the
 HTML5/W3C IndexedDB API [<a href="#resources16">Resources, 16</a>]. <i>Note
 that as the web development standards bodies are transitioning to favor
 IndexedDB over webstorage, IndexedDB is expected to become a required
 component in a future version of Android.</i></p>

 <a name="section-3.5"></a><h3 id="section-3.5">3.5. API Behavioral Compatibility</h3>
 <p>The behaviors of each of the API types (managed, soft, native, and web)
 must be consistent with the preferred implementation of the upstream Android
 Open Source Project [<a href="#resources03">Resources, 3</a>]. Some specific areas
 of compatibility are:</p>
 <ul>
 <li>Devices MUST NOT change the behavior or semantics of a standard Intent</li>
 <li>Devices MUST NOT alter the lifecycle or lifecycle semantics of a
     particular type of system component (such as Service, Activity,
     ContentProvider, etc.)</li>
 <li>Devices MUST NOT change the semantics of a standard permission</li>
 </ul>
 <p>The above list is not comprehensive. The Compatibility Test Suite (CTS)
 tests significant portions of the platform for behavioral compatibility, but
 not all. It is the responsibility of the implementer to ensure behavioral
 compatibility with the Android Open Source Project.  For this reason, device
 implementers SHOULD use the source code available via the Android Open Source
 Project where possible, rather than re-implement significant parts of the
 system.</p>


 <a name="section-3.6"></a><h3 id="section-3.6">3.6. API Namespaces</h3>
 <p>Android follows the package and class namespace conventions defined by the
 Java programming language. To ensure compatibility with third-party
 applications, device implementers MUST NOT make any prohibited modifications
 (see below) to these package namespaces:</p>
 <ul>
 <li>java.*</li>
 <li>javax.*</li>
 <li>sun.*</li>
 <li>android.*</li>
 <li>com.android.*</li>
 </ul>
 <p>Prohibited modifications include:</p>
 <ul>
 <li>Device implementations MUST NOT modify the publicly exposed APIs on the
 Android platform by changing any method or class signatures, or by removing
 classes or class fields.</li>
 <li>Device implementers MAY modify the underlying implementation of the APIs,
 but such modifications MUST NOT impact the stated behavior and Java-language
 signature of any publicly exposed APIs.</li>
 <li>Device implementers MUST NOT add any publicly exposed elements (such as
 classes or interfaces, or fields or methods to existing classes or interfaces)
 to the APIs above.</li>
 </ul>
 <p>A "publicly exposed element" is any construct which is not decorated with
 the "@hide" marker as used in the upstream Android source code. In other
 words, device implementers MUST NOT expose new APIs or alter existing APIs in
 the namespaces noted above. Device implementers MAY make internal-only
 modifications, but those modifications MUST NOT be advertised or otherwise
 exposed to developers.</p>
 <p>Device implementers MAY add custom APIs, but any such APIs MUST NOT be in a
 namespace owned by or referring to another organization. For instance, device
 implementers MUST NOT add APIs to the com.google.* or similar namespace; only
 Google may do so. Similarly, Google MUST NOT add APIs to other companies'
 namespaces. Additionally, if a device implementation includes custom APIs
 outside the standard Android namespace, those APIs MUST be packaged in an
 Android shared library so that only apps that explicitly use them (via the
 <code>&lt;uses-library&gt;</code> mechanism) are affected by the increased
 memory usage of such APIs.</p>
 <p>If a device implementer proposes to improve one of the package namespaces
 above (such as by adding useful new functionality to an existing API, or
 adding a new API), the implementer SHOULD visit source.android.com and begin
 the process for contributing changes and code, according to the information on
 that site.</p>
 <p>Note that the restrictions above correspond to standard conventions for
 naming APIs in the Java programming language; this section simply aims to
 reinforce those conventions and make them binding through inclusion in this
 compatibility definition.</p>

 <a name="section-3.7"></a><h3 id="section-3.7">3.7. Virtual Machine Compatibility</h3>
 <p>Device implementations MUST support the full Dalvik Executable (DEX)
 bytecode specification and Dalvik Virtual Machine semantics [<a
 href="#resources17">Resources, 17</a>].</p>
 <p>Device implementations MUST configure Dalvik to allocate memory in
 accordance with the upstream Android platform, and as specified by the following
 table.  (See <a href="#section-7.1.1">Section 7.1.1</a> for screen size and screen
 density definitions.)</p>

 <p>Note that memory values specified below are considered minimum values,
 and device implementations MAY allocate more memory per application.</p>
 <table>
 <tbody>
 <tr>
 <td><b>Screen Size</b></td>
 <td><b>Screen Density</b></td>
 <td><b>Application Memory</b></td>
 </tr>
 <tr>
 <td>small / normal / large</td>
 <td>ldpi / mdpi</td>
 <td>16MB</td>
 </tr>
 <tr>
 <td>small / normal / large</td>
 <td>tvdpi / hdpi</td>
 <td>32MB</td>
 </tr>
 <tr>
 <td>small / normal / large</td>
 <td>xhdpi</td>
 <td>64MB</td>
 </tr>
 <tr>
 <td>small / normal / large</td>
 <td>400dpi</td>
 <td>96MB</td>
 </tr>
 <tr>
 <td>small / normal / large</td>
 <td>xxhdpi</td>
 <td>128MB</td>
 </tr>
 <tr>
 <td>small / normal / large</td>
 <td>xxxhdpi</td>
 <td>256MB</td>
 </tr>
 <tr>
 <td>xlarge</td>
 <td>mdpi</td>
 <td>32MB</td>
 </tr>
 <tr>
 <td>xlarge</td>
 <td>tvdpi / hdpi</td>
 <td>64MB</td>
 </tr>
 <tr>
 <td>xlarge</td>
 <td>xhdpi</td>
 <td>128MB</td>
 </tr>
 <tr>
 <td>xlarge</td>
 <td>400dpi</td>
 <td>192MB</td>
 </tr>
 <tr>
 <td>xlarge</td>
 <td>xxhdpi</td>
 <td>256MB</td>
 </tr>
 <tr>
 <td>xlarge</td>
 <td>xxxhdpi</td>
 <td>512MB</td>
 </tr>
 </tbody>
 </table>

 <a name="section-3.8"></a><h3 id="section-3.8">3.8. User Interface Compatibility</h3>

 <a name="section-3.8.1"></a><h4 id="section-3.8.1">3.8.1. Launcher (Home Screen)</h4>
 <p>Android includes a launcher application (home screen) and support for third party applications to replace the device
 launcher (home screen). Device implementations that allow third party applications to replace the device home screen
 MUST declare the platform feature <code>android.software.home_screen</code>.</p>

 <a name="section-3.8.2"></a><h4 id="section-3.8.2">3.8.2. Widgets</h4>
 <p>Android defines a component type and corresponding API and lifecycle that allows applications to expose an "AppWidget"
 to the end user [<a href="#resources18">Resources, 18</a>]. Device implementations that support embedding widgets on the
 home screen MUST meet the following requirements and declare support for platform feature <code>android.software.app_widgets</code>.</p>
 <ul>
  <li>Device launchers MUST include built-in support for AppWidgets, and expose user
       interface affordances to add, configure, view, and remove AppWidgets directly within the Launcher.</li>
  <li>Device implementations MUST be capable of rendering widgets that are 4 x 4 in the standard grid size.
      (See the App Widget Design Guidelines in the Android SDK documentation [<a href="#resources18">Resources, 18</a>] for details.</li>
  <li>Device implementations that include support for lock screen MUST support application widgets on the lock screen.</li>
 </ul>

 <a name="section-3.8.3"></a><h4 id="section-3.8.3">3.8.3. Notifications</h4>
 <p>Android includes APIs that allow developers to notify users of notable
 events [<a href="#resources19">Resources, 19</a>], using hardware and software
 features of the device.</p>
 <p>Some APIs allow applications to perform notifications or attract attention
 using hardware, specifically sound, vibration, and light. Device implementations
 MUST support notifications that use hardware features, as described in the SDK
 documentation, and to the extent possible with the device implementation
 hardware. For instance, if a device implementation includes a vibrator, it
 MUST correctly implement the vibration APIs. If a device implementation lacks
 hardware, the corresponding APIs MUST be implemented as no-ops. Note that this
 behavior is further detailed in <a href="#section-7">Section 7.</a></p>
 <p>Additionally, the implementation MUST correctly render all resources
 (icons, sound files, etc.) provided for in the APIs [<a
 href="#resources20">Resources, 20</a>], or in the
 Status/System Bar icon style guide [<a href="#resources21">Resources, 21</a>].
 Device implementers MAY provide an alternative user experience for
 notifications than that provided by the reference Android Open Source
 implementation; however, such alternative notification systems MUST support
 existing notification resources, as above.</p>
 <p>Android includes support for rich notifications, such as interactive
 Views for ongoing notifications. Device implementations MUST properly display
 and execute rich notifications, as documented in the Android APIs.</p>
 <a name="section-3.8.4"></a><h4 id="section-3.8.4">3.8.4. Search</h4>
 <p>Android includes APIs [<a href="#resources22">Resources, 22</a>] that allow
 developers to incorporate search into their applications, and expose their
 application's data into the global system search. Generally speaking, this
 functionality consists of a single, system-wide user interface that allows users
 to enter queries, displays suggestions as users type, and displays results. The
 Android APIs allow developers to reuse this interface to provide search within
 their own apps, and allow developers to supply results to the common global
 search user interface.</p>
 <p>Device implementations MUST include a single, shared, system-wide search
 user interface capable of real-time suggestions in response to user input.
 Device implementations MUST implement the APIs that allow developers to reuse
 this user interface to provide search within their own applications. Device
 implementations MUST implement the APIs that allow third-party applications to
 add suggestions to the search box when it is run in global search mode. If no
 third-party applications are installed that make use of this functionality,
 the default behavior SHOULD be to display web search engine results and
 suggestions.</p>
 <a name="section-3.8.5"></a><h4 id="section-3.8.5">3.8.5. Toasts</h4>
 <p>Applications can use the "Toast" API (defined in [<a
 href="#resources23">Resources, 23</a>]) to
 display short non-modal strings to the end user, that disappear after a brief
 period of time. Device implementations MUST display Toasts from applications
 to end users in some high-visibility manner.</p>

 <a name="section-3.8.6"></a><h4 id="section-3.8.6">3.8.6. Themes</h4>
 <p>Android provides "themes" as a mechanism for applications to apply styles
 across an entire Activity or application.</p>
 <p>Android includes a "Holo" theme family as a set of defined styles for
 application developers to use if they want to match the Holo theme look and
 feel as defined by the Android SDK [<a href="#resources24">Resources, 24</a>].
 Device implementations MUST NOT alter any of the Holo theme attributes exposed
 to applications [<a href="#resources25">Resources, 25</a>].</p>
 <p>Android also includes a "Device Default" theme family as a set of defined
 styles for application developers to use if they want to match the look and feel
 of the device theme as defined by the device implementer. Device implementations
 MAY modify the DeviceDefault theme attributes exposed to applications
 [<a href="#resources25">Resources, 25</a>].</p>
 <p>From version 4.4, Android now supports a new variant theme with translucent system bars,
 allowing application developers to fill the area behind the status and
 navigation bar with their app content. To enable a consistent developer
 experience in this configuration, it is important the status bar icon style
 is maintained across different device implementations. Therefore, Android
 device implementations MUST use white for system status icons (such as signal
 strength and battery level) and notifications issued by the system, unless the
 icon is indicating a problematic status
 [<a href="#resources25">Resources, 25</a>].</p>

 <a name="section-3.8.7"></a><h4 id="section-3.8.7">3.8.7. Live Wallpapers</h4>
 <p>Android defines a component type and corresponding API and lifecycle that
 allows applications to expose one or more "Live Wallpapers" to the end user
 [<a href="#resources26">Resources, 26</a>]. Live Wallpapers are animations,
 patterns, or similar images with limited input capabilities that display as a
 wallpaper, behind other applications.</p>
 <p>Hardware is considered capable of reliably running live wallpapers if it
 can run all live wallpapers, with no limitations on functionality, at a
 reasonable framerate with no adverse affects on other applications. If
 limitations in the hardware cause wallpapers and/or applications to crash,
 malfunction, consume excessive CPU or battery power, or run at unacceptably
 low frame rates, the hardware is considered incapable of running live
 wallpaper. As an example, some live wallpapers may use an Open GL 1.0 or 2.0
 context to render their content. Live wallpaper will not run reliably on
 hardware that does not support multiple OpenGL contexts because the live
 wallpaper use of an OpenGL context may conflict with other applications that
 also use an OpenGL context.</p>
 <p>Device implementations capable of running live wallpapers reliably as
 described above SHOULD implement live wallpapers. Device implementations
 determined to not run live wallpapers reliably as described above MUST NOT
 implement live wallpapers.</p>
 <a name="section-3.8.8"></a><h4 id="section-3.8.8">3.8.8. Recent Application Display</h4>
 <p>The upstream Android source code includes a user interface for
 displaying recent applications using a thumbnail image of the application's
 graphical state at the moment the user last left the application. Device
 implementations MAY alter or eliminate this user interface; however, a future
 version of Android is planned to make more extensive use of this
 functionality. Device implementations are strongly encouraged to use the
 upstream Android user interface (or a similar thumbnail-based interface)
 for recent applications, or else they may not be compatible with a future
 version of Android.</p>
 <a name="section-3.8.9"></a><h4 id="section-3.8.9">3.8.9. Input Management</h4>
 <p>Android includes support for Input Management and support for third party input method editors.
 Device implementations that allow users to use third party input methods on the device MUST declare the platform feature
 <code>android.software.input_methods</code> and support IME APIs as defined in the Android SDK documentation.</p>
 <p>Device implementations that declare the <code>android.software.input_methods</code> feature MUST provide a user-accessible mechanism
 to add and configure third party input methods. Device implementations MUST display the settings interface in response to the
 <code>android.settings.INPUT_METHOD_SETTINGS</code> intent.</p>

 <a name="section-3.8.10"></a><h4 id="section-3.8.10">3.8.10. Lock Screen Media Remote Control</h4>
 <p>Android includes support for Remote Control API that lets media applications integrate with playback controls
 that are displayed in a remote view like the device lock screen [<a href="#resources74">Resources, 74</a>]. Device implementations
 that support lock screen in the device and allow users to add widgets on the home screen MUST
 include support for embedding remote controls in the device lock screen [<a href="#resources69">Resources, 69</a>].</p>

 <a name="section-3.8.11"></a><h4 id="section-3.8.11">3.8.11. Dreams</h4>
 <p>Android includes support for interactive screensavers called Dreams [<a href="#resources76">Resources, 76</a>].
 Dreams allows users to interact with applications when a charging device is idle, or docked in a desk dock. Device implementations
 MUST include support for Dreams and provide a settings option for users to configure Dreams.</p>

 <a name="section-3.8.12"></a><h4 id="section-3.8.12">3.8.12. Location</h4>
 <p>Location modes MUST be displayed in the Location menu within Settings [<a
 href="#resources87">Resources, 87</a>]. Location services provided through the
 <code>SettingInjectorService</code> introduced in Android 4.4 must be displayed
 in the same Location menu [<a href="#resources89">Resources, 89</a>].</p>

 <a name="section-3.8.13"></a><h4 id="section-3.8.13">3.8.13. Unicode</h4>
 <p>Android 4.4 includes support for color emoji characters. Android device
 implementations MUST provide an input method to the user for the Emoji
 characters defined in Unicode 6.1 [<a href="#resources82">Resources, 82</a>]
 and MUST be capable of rendering these emoji characters in color glyph.</p>

 <a name="section-3.9"></a><h3 id="section-3.9">3.9. Device Administration</h3>
 <p>Android includes features that allow security-aware applications
 to perform device administration functions at the system level, such as enforcing
 password policies or performing remote wipe, through the Android Device
 Administration API [<a href="#resources27">Resources, 27</a>]. Device
 implementations MUST provide an implementation of the <code>DevicePolicyManager</code>
 class [<a href="#resources28">Resources, 28</a>]. Device implementations that include support for lock screen
 MUST support the full range of device administration policies defined in the Android SDK
 documentation [<a href="#resources27">Resources, 27</a>].</p>
 <p>Device implementations MAY have a preinstalled application performing device
 administration functions but this application MUST NOT be set out-of-the box
 as the default Device Owner app [<a href="#resources84">Resources, 84</a>].</p>

 <a name="section-3.10"></a><h3 id="section-3.10">3.10. Accessibility</h3>
 <p>Android provides an accessibility layer that helps users with disabilities
 to navigate their devices more easily. In addition, Android provides
 platform APIs that enable accessibility service implementations to receive
 callbacks for user and system events and generate alternate feedback mechanisms,
 such as text-to-speech, haptic feedback, and trackball/d-pad navigation
 [<a href="#resources29">Resources, 29</a>]. Device implementations MUST provide an
 implementation of the Android accessibility framework consistent with the
 default Android implementation.  Specifically, device implementations MUST meet
 the following requirements.</p>
 <ul>
  <li>Device implementations MUST support third party accessibility service
      implementations through the <code>android.accessibilityservice</code>
      APIs [<a href="#resources30">Resources, 30</a>].</li>
  <li>Device implementations MUST generate <code>AccessibilityEvents</code>
      and deliver these events to all registered <code>AccessibilityService
      </code> implementations in a manner consistent with the default Android
      implementation.</li>
  <li>Device implementations MUST provide a user-accessible mechanism to enable
      and disable accessibility services, and MUST display this interface in
      response to the
      <code>android.provider.Settings.ACTION_ACCESSIBILITY_SETTINGS</code>
      intent.</li>
 </ul>
 <p>Additionally, device implementations SHOULD provide an implementation
 of an accessibility service on the device, and SHOULD provide a mechanism
 for users to enable the accessibility service during device setup.  An open
 source implementation of an accessibility service is available from the Eyes
 Free project [<a href="#resources31">Resources, 31</a>].</p>

 <a name="section-3.11"></a><h3 id="section-3.11">3.11. Text-to-Speech</h3>
 <p>Android includes APIs that allow applications to make use of
 text-to-speech (TTS) services, and allows service providers to provide
 implementations of TTS services [<a href="#resources32">Resources, 32</a>].
 Device implementations MUST meet these requirements related to the Android TTS
 framework:</p>
 <ul>
   <li>Device implementations MUST support the Android TTS framework APIs and
       SHOULD include a TTS engine supporting the languages available on the
       device. Note that the upstream Android open source software includes a
       full-featured TTS engine implementation.</li>
   <li>Device implementations MUST support installation of third-party TTS
       engines.</li>
   <li>Device implementations MUST provide a user-accessible interface that allows
       users to select a TTS engine for use at the system level.</li>
 </ul>

 <a name="section-4"></a><h2 id="section-4">4. Application Packaging Compatibility</h2>
 <p>Device implementations MUST install and run Android ".apk" files as
 generated by the "aapt" tool included in the official Android SDK [<a
 href="#resources33">Resources, 33</a>].</p>
 <p>Devices implementations MUST NOT extend either the .apk [<a
 href="#resources34">Resources, 34</a>], Android Manifest [<a
 href="#resources35">Resources, 35</a>],
 Dalvik bytecode [<a href="#resources17">Resources, 17</a>], or renderscript
 bytecode formats in such a way that would prevent those files from installing
 and running correctly on other compatible devices. Device implementers SHOULD
 use the reference upstream implementation of Dalvik, and the reference
 implementation's package management system.</p>

 <a name="section-5"></a><h2 id="section-5">5. Multimedia Compatibility</h2>
 <p>Device implementations MUST include at least one form of audio output, such as
 speakers, headphone jack, external speaker connection, etc.</p>
 <a name="section-5.1"></a><h3 id="section-5.1">5.1. Media Codecs</h3>
 <p>Device implementations MUST support the core media formats specified
 in the Android SDK documentation [<a href="#resources58">Resources, 58</a>] except
 where explicitly permitted in this document. Specifically, device implementations
 MUST support the media formats, encoders, decoders, file types and container
 formats defined in the tables below. All of these codecs are provided as
 software implementations in the preferred Android implementation from the Android
 Open Source Project.</p>

 <p><strong>Please note that neither Google nor the Open Handset Alliance make any
 representation that these codecs are unencumbered by third-party patents.
 Those intending to use this source code in hardware or software products are
 advised that implementations of this code, including in open source software
 or shareware, may require patent licenses from the relevant patent
 holders.</strong></p>

 <p>Note that these tables do not list specific bitrate requirements for
 most video codecs because current device hardware does not necessarily support
 bitrates that map exactly to the required bitrates specified by the relevant
 standards. Instead, device implementations SHOULD support the highest bitrate
 practical on the hardware, up to the limits defined by the specifications.</p>
 <div style="page-break-before: always;"></div>
 <table>
 <tbody>

 <tr>
 <th>Type</th>
 <th>Format / Codec</th>
 <th>Encoder</th>
 <th>Decoder</th>
 <th>Details</th>
 <th>File Type(s) / Container Formats</th>
 </tr>

 <tr>
 <td rowspan="11">Audio</td>
 <td>MPEG-4 AAC Profile (AAC LC)</td>
 <td>REQUIRED for device implementations that include microphone hardware
 and define <code>android.hardware.microphone</code>.</td>
 <td style="text-align: center;">REQUIRED</td>
 <td rowspan="1"> Support for mono/stereo/5.0/5.1* content with standard sampling rates from 8 to 48 kHz.</td>
 <td rowspan="4">
   <ul>
     <li>3GPP (.3gp)</li>
     <li>MPEG-4 (.mp4, .m4a)</li>
     <li>ADTS raw AAC (.aac, decode in Android 3.1+, encode in Android 4.0+, ADIF not supported)</li>
     <li>MPEG-TS (.ts, not seekable, Android 3.0+)</li>
   </ul>
 </td>
 </tr>

 <tr>
 <td>MPEG-4 HE AAC Profile (AAC+)</td>
 <td>REQUIRED for device implementations that include microphone hardware and define android.hardware.microphone</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>Support for mono/stereo/5.0/5.1* content with standard sampling rates from 16 to 48 kHz.</td>
 </tr>

 <tr>
 <td>MPEG-4 HE AAC v2 Profile (enhanced AAC+)</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>Support for mono/stereo/5.0/5.1* content with standard sampling rates from 16 to 48 kHz.</td>
 </tr>

 <tr>
 <td>MPEG-4 Audio Object Type ER AAC ELD (Enhanced Low Delay AAC)</td>
 <td>REQUIRED for device implementations that include microphone hardware and define android.hardware.microphone</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>Support for mono/stereo content with standard
 sampling rates from 16 to 48 kHz.</td>
 </tr>

 <tr>
 <td>AMR-NB</td>
 <td>REQUIRED for device implementations that include microphone hardware
 and define <code>android.hardware.microphone</code>.</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>4.75 to 12.2 kbps sampled @ 8kHz</td>
 <td>3GPP (.3gp)
 </td>
 </tr>

 <tr>
 <td>AMR-WB</td>
 <td>REQUIRED for device implementations that include microphone hardware
 and define <code>android.hardware.microphone</code>.</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>9 rates from 6.60 kbit/s to 23.85 kbit/s sampled @ 16kHz</td>
 <td>3GPP (.3gp)</td>
 </tr>

 <tr>
 <td>FLAC</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED<br/><small>(Android 3.1+)</small></td>
 <td>Mono/Stereo (no multichannel). Sample rates up to 48 kHz (but up to 44.1
 kHz is recommended on devices with 44.1 kHz output, as the 48 to 44.1 kHz
 downsampler does not include a low-pass filter). 16-bit recommended;
 no dither applied for 24-bit.
 </td>
 <td>FLAC (.flac) only</td>
 </tr>

 <tr>
 <td>MP3</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>Mono/Stereo 8-320Kbps constant (CBR) or variable bit-rate (VBR)
 </td>
 <td>MP3 (.mp3)</td>
 </tr>

 <tr>
 <td>MIDI</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>MIDI Type 0 and 1. DLS Version 1 and 2. XMF and Mobile XMF. Support for ringtone formats RTTTL/RTX, OTA, and iMelody </td>
 <td>
   <ul>
     <li>Type 0 and 1 (.mid, .xmf, .mxmf)</li>
     <li>RTTTL/RTX (.rtttl, .rtx)</li>
     <li>OTA (.ota)</li>
     <li>iMelody (.imy)</li>
   </ul>
 </td>
 </tr>

 <tr>
 <td>Vorbis</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>&nbsp;</td>
 <td>
   <ul>
     <li>Ogg (.ogg)</li>
     <li>Matroska (.mkv)</li>
   </ul>
 </td>
 </tr>

 <tr>
 <td>PCM/WAVE</td>
 <td style="text-align: center;">REQUIRED</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>8-bit and 16-bit linear PCM** (rates up to limit of hardware).Devices MUST support sampling rates
 for raw PCM recording at 8000,16000 and 44100 Hz frequencies</td>
 <td>WAVE (.wav)</td>
 </tr>

 <tr>
 <td rowspan="5">Image</td>
 <td>JPEG</td>
 <td style="text-align: center;">REQUIRED</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>Base+progressive</td>
 <td>JPEG (.jpg)</td>
 </tr>

 <tr>
 <td>GIF</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>&nbsp;</td>
 <td>GIF (.gif)</td>
 </tr>

 <tr>
 <td>PNG</td>
 <td style="text-align: center;">REQUIRED</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>&nbsp;</td>
 <td>PNG (.png)</td>
 </tr>

 <tr>
 <td>BMP</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>&nbsp;</td>
 <td>BMP (.bmp)</td>
 </tr>


 <tr>
 <td>WEBP</td>
 <td style="text-align: center;">REQUIRED</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>&nbsp;</td>
 <td>WebP (.webp)</td>
 </tr>

 <tr>
 <td rowspan="5">Video</td>
 <td>H.263</td>
 <td>REQUIRED for device implementations that include camera hardware
 and define <code>android.hardware.camera</code> or
 <code>android.hardware.camera.front</code>.</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>&nbsp;</td>
 <td>
   <ul>
     <li>3GPP (.3gp)</li>
     <li>MPEG-4 (.mp4)</li>
   </ul>
 </td>
 </tr>

 <tr>
 <td>H.264 AVC</td>
 <td>REQUIRED for device implementations that include camera hardware
 and define <code>android.hardware.camera</code> or
 <code>android.hardware.camera.front</code>.</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>Baseline Profile (BP)</td>
 <td>
   <ul>
     <li>3GPP (.3gp)</li>
     <li>MPEG-4 (.mp4)</li>
     <li>MPEG-TS (.ts, AAC audio only, not seekable, Android 3.0+)</li>
   </ul>
 </td>
 </tr>

 <tr>
 <td>MPEG-4 SP</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED</td>
 <td>&nbsp;</td>
 <td>3GPP (.3gp)</td>
 </tr>

 <tr>
 <td>VP8****</td>
 <td style="text-align: center;">REQUIRED<br/><small>(Android 4.3+)</small></td>
 <td style="text-align: center;">REQUIRED<br/><small>(Android 2.3.3+)</small></td>
 <td>&nbsp;</td>
 <td><a href="http://www.webmproject.org/">WebM</a> (.webm) and Matroska (.mkv, Android 4.0+)***</td>
 </tr>

 <tr>
 <td>VP9</td>
 <td>&nbsp;</td>
 <td style="text-align: center;">REQUIRED<br/><small>(Android 4.4+)</small></td>
 <td>&nbsp;</td>
 <td><a href="http://www.webmproject.org/">WebM</a> (.webm) and Matroska (.mkv,
 Android 4.0+)***</td>
 </tr>

 </tbody></table>
 <ul>
 <li>*Note: Only downmix of 5.0/5.1 content is required; recording or rendering more than 2 channels is optional.</li>
 <li>**Note: 16-bit linear PCM capture is mandatory. 8-bit linear PCM capture is not mandatory.</li>
 <li>***Note: Device implementations SHOULD support writing Matroska WebM files.</li>
 <li>****Note: For acceptable quality of web video streaming and video-conference
 services, device implementations SHOULD use a hardware VP8 codec that meets the
 requirements in [<a href="#resources86">Resources, 86</a>].</li>
 </ul>

 <a name="section-5.2"></a><h3 id="section-5.2">5.2. Video Encoding</h3>
 <p>Android device implementations that include a rear-facing camera and declare
 <code>android.hardware.camera</code> SHOULD support the following H.264 video encoding
 profiles.</p>
 <table>
   <thead>
   <tr>
     <th>&nbsp;</th>
     <th>SD (Low quality)</th>
     <th>SD (High quality)</th>
     <th>HD (When supported by hardware)</th>
   </tr>
   </thead>
   <tbody>
   <tr>
     <th>Video resolution</th>
     <td>176 x 144 px</td>
     <td>480 x 360 px</td>
     <td>1280 x 720 px</td>
   </tr>
   <tr>
     <th>Video frame rate</th>
     <td>12 fps</td>
     <td>30 fps</td>
     <td>30 fps</td>
   </tr>
   <tr>
     <th>Video bitrate</th>
     <td>56 Kbps</td>
     <td>500 Kbps or higher</td>
     <td>2 Mbps or higher</td>
   </tr>
   <tr>
     <th>Audio codec</th>
     <td>AAC-LC</td>
     <td>AAC-LC</td>
     <td>AAC-LC</td>
   </tr>
   <tr>
     <th>Audio channels</th>
     <td>1 (mono)</td>
     <td>2 (stereo)</td>
     <td>2 (stereo)</td>
   </tr>
   <tr>
     <th>Audio bitrate</th>
     <td>24 Kbps</td>
     <td>128 Kbps</td>
     <td>192 Kbps</td>
   </tr>
   </tbody>
 </table>

 <p>Android device implementations that include a rear-facing camera and declare
 <code>android.hardware.camera</code> SHOULD support the following VP8 video encoding profiles</p>
 <table>
   <thead>
   <tr>
     <th>&nbsp;</th>
     <th>SD (Low quality)</th>
     <th>SD (High quality)</th>
     <th>HD 720p <br/> (When supported by hardware)</th>
     <th>HD 1080p <br/>(When supported by hardware)</th>
   </tr>
   </thead>
   <tbody>
   <tr>
     <th>Video resolution</th>
     <td>320 x 180 px</td>
     <td>640 x 360 px</td>
     <td>1280 x 720 px</td>
     <td>1920 x 1080 px</td>
   </tr>
   <tr>
     <th>Video frame rate</th>
     <td>30 fps</td>
     <td>30 fps</td>
     <td>30 fps</td>
     <td>30 fps</td>
   </tr>
   <tr>
     <th>Video bitrate</th>
     <td>800 Kbps</td>
     <td>2 Mbps</td>
     <td>4 Mbps</td>
     <td>10 Mbps</td>
   </tr>
   </tbody>
 </table>

 <a name="section-5.3"></a><h3 id="section-5.3">5.3. Video Decoding</h3>
 <p>Android device implementations SHOULD support the following VP8, VP9 and
 H.264 video decoding profiles. Device implementations SHOULD also support
 dynamic video resolution switching within the same stream for VP8, VP9 and
 H.264 codecs.</p>
 <table>
   <thead>
   <tr>
     <th>&nbsp;</th>
     <th>SD (Low quality)</th>
     <th>SD (High quality)</th>
     <th>HD 720p <br/> (When supported by hardware)</th>
     <th>HD 1080p <br/>(When supported by hardware)</th>
   </tr>
   </thead>
   <tbody>
   <tr>
     <th>Video resolution</th>
     <td>320 x 180 px</td>
     <td>640 x 360 px</td>
     <td>1280 x 720 px</td>
     <td>1920 x 1080 px</td>
   </tr>
   <tr>
     <th>Video frame rate</th>
     <td>30 fps</td>
     <td>30 fps</td>
     <td>30 fps</td>
     <td>30 fps</td>
   </tr>
   <tr>
     <th>Video bitrate</th>
     <td>800 Kbps</td>
     <td>2 Mbps</td>
     <td>8 Mbps</td>
     <td>20 Mbps</td>
   </tr>
   </tbody>
 </table>

 <a name="section-5.4"></a><h3 id="section-5.4">5.4. Audio Recording</h3>
 <p>When an application has used the <code>android.media.AudioRecord</code> API to
 start recording an audio stream, device implementations that include microphone
 hardware and declare <code>android.hardware.microphone</code> MUST sample and
 record audio with each of these behaviors:</p>
 <ul>
 <li>The device SHOULD exhibit approximately flat amplitude versus frequency
     characteristics; specifically, &plusmn;3 dB, from 100 Hz to 4000 Hz</li>
 <li>Audio input sensitivity SHOULD be set such that a 90 dB sound power level
     (SPL) source at 1000 Hz yields RMS of 2500 for 16-bit samples.</li>
 <li>PCM amplitude levels SHOULD linearly track input SPL changes over at least
     a 30 dB range from -18 dB to +12 dB re 90 dB SPL at the microphone.</li>
 <li>Total harmonic distortion SHOULD be less than 1% for 1Khz at 90 dB SPL input level.</li>
 </ul>
 <p>In addition to the above recording specifications, when an application has
 started recording an audio stream using the
 <code>android.media.MediaRecorder.AudioSource.VOICE_RECOGNITION</code> audio
 source:</p>
 <ul>
 <li>Noise reduction processing, if present, MUST be disabled.</li>
 <li>Automatic gain control, if present, MUST be disabled.</li>
 </ul>
 <p>From Android 4.4, <code>android.media.MediaRecorder.AudioSource</code> class has a new
 audio source: <code>REMOTE_SUBMIX</code>. Devices MUST properly implement the
 <code>REMOTE_SUBMIX</code> audio source so that when an application uses the
 <code>android.media.AudioRecord</code> API to record from this audio source,
 it can capture a mix of all audio streams except for the following:</p>
 <ul>
 <li><code>STREAM_RING</code></li>
 <li><code>STREAM_ALARM</code></li>
 <li><code>STREAM_NOTIFICATION</code></li>
 </ul>
 <p><b>Note:</b> while some of the requirements outlined above are stated as
 "SHOULD" since Android 4.3, the Compatibility Definition for a future version
 is planned to change these to "MUST". That is, these requirements are optional
 in Android 4.4 but <b>will be required</b> by a future version. Existing and new
 devices that run Android are <b>very strongly encouraged to meet these
 requirements</b>, or they will not be able to attain Android
 compatibility when upgraded to the future version.</p>
 <p>If the platform supports noise suppression technologies tuned for speech
 recognition, the effect MUST be controllable from the
 <code>android.media.audiofx.NoiseSuppressor</code> API. Moreover, the "uuid"
 field for the noise suppressor's effect descriptor MUST uniquely identify each
 implementation of the noise suppression technology.</p>

 <a name="section-5.5"></a><h3 id="section-5.5">5.5. Audio Latency</h3>
 <p>Audio latency is the time delay as an audio signal passes through a system.
 Many classes of
 applications rely on short latencies, to achieve real-time sound effects.</p>
 <p>For the purposes of this section:</p>
 <ul>
 <li>"output latency" is defined as the interval between when an application
 writes a frame of PCM-coded data and when the corresponding sound can be heard
 by an external listener or observed by a transducer</li>
 <li>"cold output latency" is defined as the output latency for the first frame, when
     the audio output system has been idle and powered down prior to the request</li>
 <li>"continuous output latency" is defined as the output latency for subsequent frames,
     after the device is already playing audio</li>
 <li>"input latency" is the interval between when an external sound is presented
 to the device and when an application reads the corresponding frame of PCM-coded data</li>
 <li>"cold input latency" is defined as the sum of lost input time
     and the input latency for the first frame, when
     the audio input system has been idle and powered down prior to the request</li>
 <li>"continuous input latency" is defined as the input latency for subsequent frames,
     while the device is already capturing audio</li>
 <li>"OpenSL ES PCM buffer queue API" is the set of PCM-related OpenSL ES APIs within Android NDK;
 see <i>NDK_root</i><code>/docs/opensles/index.html</code></li>
 </ul>
 <p>Per <a href="#section-5">Section 5</a>,
 all compatible device implementations MUST include at least one form of audio output.
 Device implementations SHOULD meet or exceed these output latency requirements:</p>
 <ul>
 <li>cold output latency of 100 milliseconds or less</li>
 <li>continuous output latency of 45 milliseconds or less</li>
 </ul>
 <p>If a device implementation meets the requirements of this section
 after any initial calibration
 when using the OpenSL ES PCM buffer queue API,
 for continuous output latency and cold output latency
 over at least one supported audio output device, it MAY
 report support for low-latency audio, by reporting the feature
 "android.hardware.audio.low-latency" via the
 <code>android.content.pm.PackageManager</code> class. [<a
 href="#resources37">Resources, 37</a>] Conversely, if the device
 implementation does not meet these requirements it MUST NOT report support for
 low-latency audio.</p>
 <p>
 Per <a href="#section-7.2.5">Section 7.2.5</a>,
 microphone hardware may be omitted by device implementations.</p>
 <p>
 Device implementations that include microphone
 hardware and declare <code>android.hardware.microphone</code> SHOULD
 meet these input audio latency requirements:</p>
 <ul>
 <li>cold input latency of 100 milliseconds or less</li>
 <li>continuous input latency of 50 milliseconds or less</li>
 </ul>

 <a name="section-5.6"></a><h3 id="section-5.6">5.6. Network Protocols</h3>
 <p>Devices MUST support the media network protocols for audio and video playback
 as specified in the Android SDK documentation
 [<a href="#resources58">Resources, 58</a>].  Specifically, devices MUST support
 the following media network protocols:</p>
 <ul>
 <li>RTSP (RTP, SDP)</li>
 <li>HTTP(S) progressive streaming</li>
 <li>HTTP(S) Live Streaming draft protocol, Version 3 [<a href="#resources59">Resources, 59</a>]</li>
 </ul>
 <a name="section-6"></a><h2 id="section-6">6. Developer Tools and Options Compatibility</h2>

 <a name="section-6.1"></a><h3 id="section-6.1">6.1. Developer Tools</h3>
 <p>Device implementations MUST support the Android Developer Tools provided in the Android SDK.
 Specifically, Android-compatible devices MUST be compatible with:</p>
 <ul>
 <li><b>Android Debug Bridge (known as adb)</b> [<a href="#resources33">Resources, 33</a>]<br/>
 Device implementations MUST support all <code>adb</code> functions as
 documented in the Android SDK. The device-side <code>adb</code> daemon MUST
 be inactive by default, and there MUST be a user-accessible mechanism to turn
 on the Android Debug Bridge.</li>
 <li>Android includes support for secure adb. Secure adb enables adb on known authenticated hosts.
 Device implementations MUST support secure adb.</li>
 <li><b>Dalvik Debug Monitor Service (known as ddms)</b> [<a href="#resources33">Resources, 33</a>]<br/>
 Device implementations MUST support all <code>ddms</code> features as documented in the
 Android SDK. As <code>ddms</code> uses <code>adb</code>, support for
 <code>ddms</code> SHOULD be inactive by default,
 but MUST be supported whenever the user has activated the Android Debug
 Bridge, as above.</li>
 <li><b>Monkey</b> [<a href="#resources36">Resources, 36</a>]<br/>
 Device implementations MUST include the Monkey framework, and make it
 available for applications to use.</li>
 <li><b>SysTrace</b> [<a href="#resources33">Resources, 33</a>]<br/>
 Device implementations MUST support systrace tool as documented in the Android SDK.
 Systrace must be inactive by default, and there MUST be a user-accessible mechanism to turn
 on Systrace.</li>
 </ul>
 <p>Most Linux-based systems and Apple Macintosh systems recognize Android
 devices using the standard Android SDK tools, without additional support;
 however Microsoft Windows systems typically require a driver for new Android
 devices. (For instance, new vendor IDs and sometimes new device IDs require
 custom USB drivers for Windows systems.) If a device implementation is
 unrecognized by the <code>adb</code> tool as provided in the standard Android
 SDK, device implementers MUST provide Windows drivers allowing developers to
 connect to the device using the <code>adb</code> protocol. These drivers MUST
 be provided for Windows XP, Windows Vista, Windows 7, and Windows 8, in both 32-bit and
 64-bit versions.</p>

 <a name="section-6.2"></a><h3 id="section-6.2">6.2. Developer Options</h3>
 <p>Android includes support for developers to configure application development-related settings.
 Device implementations MUST honor the android.settings.APPLICATION_DEVELOPMENT_SETTINGS intent to show
 application development-related settings [<a href="#resources77">Resources, 77</a>]. The upstream Android
 implementation hides the Developer Options menu by default, and enables users to launch Developer Options
 after pressing seven (7) times on the Settings > About Device > Build Number menu item. Device implementations
 MUST provide a consistent experience for Developer Options. Specifically, device implementations MUST hide
 Developer Options by default and MUST provide a mechanism to enable Developer Options that is consistent with
 the upstream Android implementation.</p>

 <a name="section-6.2.1"></a><h4 id="section-6.2.1">6.2.1. Experimental</h4>
 <p>Android 4.4 introduces ART, an experimental Android runtime, accessible
 within the Developer Options menu for preview. Device
 implementations SHOULD include ART (libart.so) and support dual boot from
 Developer Options, but MUST keep Dalvik (libdvm.so) as the default runtime.</p>

 <a name="section-7"></a><h2 id="section-7">7. Hardware Compatibility</h2>
 <p>If a device includes a particular hardware component that has a
 corresponding API for third-party developers, the device implementation MUST
 implement that API as described in the Android SDK documentation. If an API in
 the SDK interacts with a hardware component that is stated to be optional and
 the device implementation does not possess that component:</p>
 <ul>
 <li>complete class definitions (as documented by the SDK) for the component's
 APIs MUST still be present</li>
 <li>the API's behaviors MUST be implemented as no-ops in some reasonable
 fashion</li>
 <li>API methods MUST return null values where permitted by the SDK
 documentation</li>
 <li>API methods MUST return no-op implementations of classes where null
 values are not permitted by the SDK documentation</li>
 <li>API methods MUST NOT throw exceptions not documented by the SDK
 documentation</li>
 </ul>
 <p>A typical example of a scenario where these requirements apply is the
 telephony API: even on non-phone devices, these APIs must be implemented as
 reasonable no-ops.</p>
 <p>Device implementations MUST accurately report accurate hardware configuration
 information via the <code>getSystemAvailableFeatures()</code> and
 <code>hasSystemFeature(String)</code> methods on the
 <code>android.content.pm.PackageManager</code> class. [<a
 href="#resources37">Resources, 37</a>]</p>

 <a name="section-7.1"></a><h3 id="section-7.1">7.1. Display and Graphics</h3>
 <p>Android includes facilities that automatically adjust application
 assets and UI layouts appropriately for the device, to ensure that third-party
 applications run well on a variety of hardware configurations [<a
 href="#resources38">Resources, 38</a>]. Devices MUST properly implement these
 APIs and behaviors, as detailed in this section.</p>

 <p>The units referenced by the requirements in this section are defined as follows:</p>
 <ul>
 <li>"Physical diagonal size" is the distance in inches between two opposing
 corners of the illuminated portion of the display.</li>
 <li>"dpi" (meaning "dots per inch") is the number of pixels encompassed by a
 linear horizontal or vertical span of 1". Where dpi values are listed, both
 horizontal and vertical dpi must fall within the range.</li>
 <li>"Aspect ratio" is the ratio of the longer dimension of the screen to the
 shorter dimension. For example, a display of 480x854 pixels would be 854 / 480
 = 1.779, or roughly "16:9".</li>
 <li>A "density-independent pixel" or ("dp") is the virtual pixel unit normalized to a
 160 dpi screen, calculated as:
 <code>pixels = dps * (density / 160)</code>.</li>
 </ul>


 <a name="section-7.1.1"></a><h4 id="section-7.1.1">7.1.1. Screen Configuration</h4>

 <p style="font-weight:bold;">Screen Size</p>
 <p>The Android UI framework supports a variety of different screen sizes, and
 allows applications to query the device screen size (aka "screen layout") via
 <code>android.content.res.Configuration.screenLayout</code> with the
 <code>SCREENLAYOUT_SIZE_MASK</code>. Device implementations MUST report the
 correct screen size as defined in the Android SDK documentation
 [<a href="#resources38">Resources, 38</a>] and determined by the upstream
 Android platform. Specifically, device implementations must report the correct
 screen size according to the following logical density-independent pixel (dp)
 screen dimensions.</p>
 <ul>
 <li>Devices MUST have screen sizes of at least 426 dp x 320 dp ('small')</li>
 <li>Devices that report screen size 'normal' MUST have screen sizes of at least
 480 dp x 320 dp</li>
 <li>Devices that report screen size 'large' MUST have screen sizes of at least
 640 dp x 480 dp</li>
 <li>Devices that report screen size 'xlarge' MUST have screen sizes of at least
 960 dp x 720 dp</li>
 </ul>
 <p>In addition, devices MUST have screen sizes of at least 2.5 inches in
 physical diagonal size.</p>

 <p>Devices MUST NOT change their reported screen size at any time.</p>
 <p>Applications optionally indicate which screen sizes they support via the
 <code>&lt;supports-screens&gt;</code> attribute in the AndroidManifest.xml
 file. Device implementations MUST correctly honor applications' stated support
 for small, normal, large, and xlarge screens, as described in the Android
 SDK documentation.</p>

 <p style="font-weight:bold;">Screen Aspect Ratio</p>
 <p>The aspect ratio MUST be a value from 1.3333 (4:3) to 1.86 (roughly 16:9)</p>

 <p style="font-weight:bold;">Screen Density</p>
 <p>The Android UI framework defines a set of standard logical densities to
 help application developers target application resources. Device
 implementations MUST report one of the following logical Android framework
 densities through the <code>android.util.DisplayMetrics</code> APIs, and MUST
 execute applications at this standard density.
 <ul>
 <li>120 dpi, known as 'ldpi'</li>
 <li>160 dpi, known as 'mdpi'</li>
 <li>213 dpi, known as 'tvdpi'</li>
 <li>240 dpi, known as 'hdpi'</li>
 <li>320 dpi, known as 'xhdpi'</li>
 <li>400 dpi, known as '400dpi'</li>
 <li>480 dpi, known as 'xxhdpi'</li>
 <li>640 dpi, known as 'xxxhdpi'</li>
 </ul>
 Device implementations SHOULD define the standard Android framework density
 that is numerically closest to the physical density of the screen, unless that
 logical density pushes the reported screen size below the minimum supported.
 If the standard Android framework density that is numerically closest to the
 physical density results in a screen size that is smaller than the smallest
 supported compatible screen size (320 dp width), device implementations SHOULD
 report the next lowest standard Android framework density.</p>

 <a name="section-7.1.2"></a><h4 id="section-7.1.2">7.1.2. Display Metrics</h4>
 <p>Device implementations MUST report correct values for all display metrics
 defined in <code>android.util.DisplayMetrics</code> [<a
 href="#resources39">Resources, 39</a>].</p>

 <a name="section-7.1.3"></a><h4 id="section-7.1.3">7.1.3. Screen Orientation</h4>
 <p>Devices MUST support dynamic orientation by applications to
 either portrait or landscape screen orientation. That is, the device must
 respect the application's request for a specific screen orientation. Device
 implementations MAY select either portrait or landscape orientation as the
 default.</p>
 <p>Devices MUST report the correct value for the device's current orientation,
 whenever queried via the android.content.res.Configuration.orientation,
 android.view.Display.getOrientation(), or other APIs.</p>
 <p>Devices MUST NOT change the reported screen size or density when changing
 orientation.</p>
 <p>Devices MUST report which screen orientations they support (
 <code>android.hardware.screen.portrait</code> and/or
 <code>android.hardware.screen.landscape</code>) and MUST report at least one
 supported orientation.  For example, a device with a fixed-orientation
 landscape screen, such as a television or laptop, MUST only report
 <code>android.hardware.screen.landscape</code>.</p>

 <a name="section-7.1.4"></a><h4 id="section-7.1.4">7.1.4. 2D and 3D Graphics Acceleration</h4>
 <p>Device implementations MUST support both OpenGL ES 1.0 and 2.0, as embodied
 and detailed in the Android SDK documentations. Device implementations SHOULD support
 OpenGL ES 3.0 on devices capable of supporting OpenGL ES 3.0.
 Device implementations MUST also support Android Renderscript, as detailed in the Android SDK
 documentation [<a href="#resources08">Resources, 8</a>].</p>
 <p>Device implementations MUST also correctly identify themselves as
 supporting OpenGL ES 1.0, OpenGL ES 2.0, or OpenGL ES 3.0. That is:</p>
 <ul>
 <li>The managed APIs (such as via the <code>GLES10.getString()</code> method)
 MUST report support for OpenGL ES 1.0 and OpenGL ES 2.0 </li>
 <li>The native C/C++ OpenGL APIs (that is, those available to apps via
 libGLES_v1CM.so, libGLES_v2.so, or libEGL.so) MUST report support for
 OpenGL ES 1.0 and OpenGL ES 2.0.</li>
 <li>Device implementations that declare support for OpenGL ES 3.0 MUST support
 OpenGL ES 3.0 managed APIs and include support for native C/C++ APIs. On device
 implementations that declare support for OpenGL ES 3.0, libGLESv2.so MUST export the OpenGL ES 3.0
 function symbols in addition to the OpenGL ES 2.0 function symbols.
 </li>
 </ul>

 <p>Device implementations MAY implement any desired OpenGL ES extensions.
 However, device implementations MUST report via the OpenGL ES managed and
 native APIs all extension strings that they do support, and conversely MUST
 NOT report extension strings that they do not support.</p>
 <p>Note that Android includes support for applications to optionally
 specify that they require specific OpenGL texture compression formats. These
 formats are typically vendor-specific. Device implementations are not required
 by Android to implement any specific texture compression format. However,
 they SHOULD accurately report any texture compression formats that they do
 support, via the <code>getString()</code> method in the OpenGL API.</p>

 <p>Android includes a mechanism for applications to declare that they
 wanted to enable hardware acceleration for 2D graphics at the Application,
 Activity, Window or View level through the use of a manifest tag
 <code>android:hardwareAccelerated</code> or direct API calls
 [<a href="#resources09">Resources, 9</a>].</p>
 <p>In Android 4.4, device implementations MUST enable hardware acceleration by
 default, and MUST disable hardware acceleration if the developer so requests
 by setting <code>android:hardwareAccelerated="false"</code> or disabling
 hardware acceleration directly through the Android View APIs.</p>
 <p>In addition, device implementations MUST exhibit behavior consistent with the
 Android SDK documentation on hardware acceleration
 [<a href="#resources09">Resources, 9</a>].</p>
 <p>Android includes a <code>TextureView</code> object that lets developers
 directly integrate hardware-accelerated OpenGL ES textures as rendering targets
 in a UI hierarchy. Device implementations MUST support the <code>TextureView
 </code> API, and MUST exhibit consistent behavior with the upstream Android
 implementation.</p>
 <p>Android includes support for <code>EGL_ANDROID_RECORDABLE</code>, a EGLConfig attribute
 that indicates whether the EGLConfig supports rendering to an ANativeWindow that records images to a video.
 Device implementations MUST support <code>EGL_ANDROID_RECORDABLE</code> extension [<a href="#resources79">Resources, 79</a>].</p>

 <a name="section-7.1.5"></a><h4 id="section-7.1.5">7.1.5. Legacy Application Compatibility Mode</h4>
 <p>Android specifies a "compatibility mode" in which the framework
 operates in an 'normal' screen size equivalent (320dp width) mode for the benefit
 of legacy applications not developed for old versions of Android that pre-date
 screen-size independence. Device implementations MUST include support for legacy
 application compatibility mode as implemented by the upstream Android open source
 code. That is, device implementations MUST NOT alter the triggers or thresholds at
 which compatibility mode is activated, and MUST NOT alter the behavior of the
 compatibility mode itself.</p>

 <a name="section-7.1.6"></a><h4 id="section-7.1.6">7.1.6. Screen Types</h4>
 <p>Device implementation screens are classified as one of two types:</p>
 <ul>
 <li>Fixed-pixel display implementations: the screen is a single panel that supports only a
 single pixel width and height. Typically the screen is physically integrated with
 the device. Examples include mobile phones, tablets, and so on.</li>
 <li>Variable-pixel display implementations: the device implementation either has no
 embedded screen and includes a video output port such as VGA, HDMI or a wireless port
 for display, or has an embedded screen that can change pixel dimensions. Examples
 include televisions, set-top boxes, and so on.</li>
 </ul>
 <p style="font-weight: bold;">Fixed-Pixel Device Implementations</p>
 <p>Fixed-pixel device implementations MAY use screens of any pixel dimensions, provided
 that they meet the requirements defined this Compatibility Definition.</p>
 <p>Fixed-pixel implementations MAY include a video output port for use with an
 external display. However, if that display is ever used for running apps, the
 device MUST meet the following requirements:</p>
 <ul>
 <li>The device MUST report the same screen configuration and display metrics, as detailed
 in Sections 7.1.1 and 7.1.2, as the fixed-pixel display.</li>
 <li>The device MUST report the same logical density as the fixed-pixel display.</li>
 <li>The device MUST report screen dimensions that are the same as, or very close to,
 the fixed-pixel display.</li>
 </ul>
 <p>For example, a tablet that is 7" diagonal size with a 1024x600 pixel resolution is
 considered a fixed-pixel large mdpi display implementation.  If it contains a video
 output port that displays at 720p or 1080p the device implementation MUST scale the output so that
 applications are only executed in a large mdpi window, regardless of whether the fixed-pixel display
 or video output port is in use.</p>

 <p style="font-weight: bold;">Variable-Pixel Device Implementations</p>
 <p>Variable-pixel device implementations MUST support at least one of 1280x720,
 1920x1080, or 3840x2160 (that is, 720p, 1080p, or 4K). Device implementations with
 variable-pixel displays MUST NOT support any other screen configuration or
 mode. Device implementations with variable-pixel screens MAY change screen
 configuration or mode at runtime or boot-time. For example, a user of a
 set-top box may replace a 720p display with a 1080p display, and the device
 implementation may adjust accordingly.</p>

 <p>Additionally, variable-pixel device implementations MUST report the following
 configuration buckets for these pixel dimensions:</p>
 <ul>
 <li>1280x720 (also known as 720p): 'large' screen size, 'tvdpi' (213 dpi)
 density</li>
 <li>1920x1080 (also known as 1080p): 'large' screen size, 'xhdpi' (320 dpi)
 density</li>
 <li>3840x2160 (also known as 4K): 'large' screen size, 'xxxhdpi' (640 dpi)
 density</li>
 </ul>
 <p>For clarity, device implementations with variable pixel dimensions are
 restricted to 720p, 1080p, or 4K in Android 4.4, and MUST be configured to report
 screen size and density buckets as noted above.</p>

 <a name="section-7.1.7"></a><h4 id="section-7.1.7">7.1.7. Screen Technology</h4>
 <p>The Android platform includes APIs that allow applications to render rich
 graphics to the display. Devices MUST support all of these APIs as defined by
 the Android SDK unless specifically allowed in this document.  Specifically:</p>
 <ul>
 <li>Devices MUST support displays capable of rendering 16-bit color graphics and
 SHOULD support displays capable of 24-bit color graphics.</li>
 <li>Devices MUST support displays capable of rendering animations.</li>
 <li>The display technology used MUST have a pixel aspect ratio (PAR) between
     0.9 and 1.1. That is, the pixel aspect ratio MUST be near square (1.0) with
     a 10% tolerance.</li>
 </ul>
 <a name="section-7.1.8"></a><h4 id="section-7.1.8">7.1.8. External Displays</h4>
 <p>Android includes support for secondary display to enable media sharing capabilities and
 developer APIs for accessing external displays. If a device supports an external display either via
 a wired, wireless or an embedded additional display connection then the device implementation MUST
 implement the display manager API as described in the Android SDK documentation [<a href="#resources75">Resources, 75</a>].
 Device implementations that support secure video output and are capable of supporting secure surfaces MUST declare support
 for <code>Display.FLAG_SECURE</code>. Specifically, device implementations that declare support for <code>Display.FLAG_SECURE</code>,
 MUST support <b>HDCP 2.x or higher</b> for Miracast wireless displays or <b>HDCP 1.2 or higher</b> for wired displays. The upstream
 Android open source implementation includes support for wireless (Miracast) and wired (HDMI) displays that satisfies this requirement.</p>

 <a name="section-7.2"></a><h3 id="section-7.2">7.2. Input Devices</h3>
 <a name="section-7.2.1"></a><h4 id="section-7.2.1">7.2.1. Keyboard</h4>
 <p>Device implementations:</p>
 <ul>
 <li>MUST include support for the Input Management Framework (which allows third
 party developers to create Input Management Engines - i.e. soft keyboard) as
 detailed at <a href="http://developer.android.com">http://developer.android.com</a>
 </li>
 <li>MUST provide at least one soft keyboard implementation (regardless of whether
 a hard keyboard is present)</li>
 <li>MAY include additional soft keyboard implementations</li>
 <li>MAY include a hardware keyboard</li>
 <li>MUST NOT include a hardware keyboard that does not match one of the
 formats specified in <code>android.content.res.Configuration.keyboard</code>
 [<a href="#resources40">Resources, 40</a>] (that is, QWERTY, or 12-key)</li>
 </ul>
 <a name="section-7.2.2"></a><h4 id="section-7.2.2">7.2.2. Non-touch Navigation</h4>
 <p>Device implementations:</p>
 <ul>
 <li>MAY omit a non-touch navigation option (that is, may omit a trackball, d-pad,
 or wheel)</li>
 <li>MUST report the correct value for
 <code>android.content.res.Configuration.navigation</code>
 [<a href="#resources40">Resources, 40</a>]</li>
 <li>MUST provide a reasonable alternative user interface mechanism for the
 selection and editing of text, compatible with Input Management Engines. The
 upstream Android open source implementation includes a selection mechanism suitable
 for use with devices that lack non-touch navigation inputs.</li>
 </ul>
 <a name="section-7.2.3"></a><h4 id="section-7.2.3">7.2.3. Navigation keys</h4>
 <p>The Home, Recents and Back functions are essential to the Android navigation
 paradigm. Device implementations MUST make these functions available to the user
 at all times when running applications. These functions MAY be implemented via
 dedicated physical buttons (such as mechanical or capacitive touch buttons), or
 MAY be implemented using dedicated software keys on a distinct portion of the
 screen, gestures, touch panel, etc. Android supports both implementations. All
 of these functions MUST be accessible with a single action (e.g. tap,
 double-click or gesture) when visible.</p>
 <p>The Back and Recents functions SHOULD have a visible button or icon unless
 hidden together with other navigation functions in full-screen mode. The Home
 function MUST have a visible button or icon unless hidden together with other
 navigation functions in full-screen mode.</p>
 <p>The Menu function is deprecated in favor of action bar since Android 4.0.
 Device implementations SHOULD NOT implement a dedicated physical button for
 the Menu function. If the physical Menu button is implemented and the device
 is running applications with <code>targetSdkVersion</code> &gt; 10, the device
 implementation:</p>
 <ul>
   <li>for a device launching with Android 4.4, MUST display the action overflow
     button on the action bar when the action bar is visible and the resulting action
     overflow menu popu is not empty.</li>
   <li>for an existing device launched with an earlier version but upgrading to
     Android 4.4, SHOULD display the action overflow button on the action bar
     when the action bar is visible and the resulting action overflow menu popup
     is not empty.</li>
   <li>MUST NOT modify the position of the action overflow popup displayed by
   selecting the overflow button in the action bar.</li>
   <li>MAY render the action overflow popup at a modified position on the screen
   when it is displayed by selecting the physical menu button.</li>
 </ul>
 <p>For backwards compatibility, device implementations MUST make available the
 Menu function to applications when <code>targetSdkVersion</code> &lt;= 10,
 either by a phsyical button, a software key or gestures. This Menu function
 should be presented unless hidden together with other navigation functions.</p>
 <p>Android supports Assist action [<a href="#resources63">Resources, 63</a>].
 Device implementations MUST make the Assist action available to the user at all
 times when running applications. The Assist action SHOULD be implemented as a
 long-press on the Home button or a swipe-up gesture on the software Home key.
 This function MAY be implemented via another physical button, software key or
 gestures, but MUST be accessible with a single action (e.g. tap, double-click or
 gesture) when other navigation keys are visible.</p>
 <p>Device implementations MAY use a distinct portion of the screen to display
 the navigation keys, but if so, MUST meet these requirements:</p>
 <ul>
   <li>Device implementation navigation keys MUST use a distinct portion of the
       screen, not available to applications, and MUST NOT obscure or otherwise
       interfere with the portion of the screen available to applications.</li>
   <li>Device implementations MUST make available a portion of the display to
       applications that meets the requirements defined in
       <a href="section-7.1.1">Section 7.1.1</a>.</li>
   <li>Device implementations MUST display the navigation keys when applications
       do not specify a system UI mode, or specify
       <code>SYSTEM_UI_FLAG_VISIBLE</code>.</li>
   <li>Device implementations MUST present the navigation keys in an unobtrusive
       "low profile" (eg. dimmed) mode when applications specify
       <code>SYSTEM_UI_FLAG_LOW_PROFILE</code>.</li>
   <li>Device implementations MUST hide the navigation keys when applications
       specify <code>SYSTEM_UI_FLAG_HIDE_NAVIGATION</code>.</li>
 </ul>
 <a name="section-7.2.4"></a><h4 id="section-7.2.4">7.2.4. Touchscreen input</h4>
 <p>Device implementations SHOULD have a pointer input system of some kind (either mouse-like, or touch). However, if a device
 implementation does not support a pointer input system, it MUST NOT report the <code>android.hardware.touchscreen</code> or
 <code>android.hardware.faketouch</code> feature constant. Device implementations that do include a pointer input system:</p>
 <ul>
 <li>SHOULD support fully independently tracked pointers, if the device input system supports multiple pointers</li>
 <li>MUST report the value of <code>android.content.res.Configuration.touchscreen</code> [<a href="#resources40">Resources, 40</a>]
 corresponding to the type of the specific touchscreen on the device</li>
 </ul>

 <p>Android includes support for a variety of touch screens, touch pads, and fake touch input devices.
 Touch screen based device implementations are associated with a display [<a href="#resources81">Resources, 81</a>]
 such that the user has the impression of directly manipulating items on screen. Since the user is directly touching the screen,
 the system does not require any additional affordances to indicate the objects being manipulated.
 In contrast, a fake touch interface provides a user input system that approximates a subset of touchscreen capabilities.
 For example, a mouse or remote control that drives an on-screen cursor approximates touch, but requires the user to first
 point or focus then click. Numerous input devices like the mouse, trackpad, gyro-based air mouse, gyro-pointer, joystick,
 and multi-touch trackpad can support fake touch interactions. Android 4.0 includes the feature constant <code>android.hardware.faketouch</code>,
 which corresponds to a high-fidelity non-touch (that is, pointer-based) input device such as a mouse or trackpad that can adequately emulate touch-based
 input (including basic gesture support), and indicates that the device supports an emulated subset of touchscreen
 functionality. Device implementations that declare the fake touch feature MUST meet the fake touch requirements in <a href="section 7.2.5">Section 7.2.5</a>.</p>

 <p>Device implementations MUST report the correct feature corresponding to the type of input used. Device implementations that
 include a touchscreen (single-touch or better) MUST report the platform feature constant <code>android.hardware.touchscreen</code>.
 Device implementations that report the platform feature constant <code>android.hardware.touchscreen</code> MUST also report the platform feature constant
 <code>android.hardware.faketouch</code>. Device implementations that do not include a touchscreen (and rely on a pointer device only) MUST NOT report any
 touchscreen feature, and MUST report only <code>android.hardware.faketouch</code> if they meet the fake touch requirements in <a href="section 7.2.5">Section 7.2.5</a>.</p>

 <a name="section-7.2.5"></a><h4 id="section-7.2.5">7.2.5. Fake touch input</h4>
 <p>Device implementations that declare support for <code>android.hardware.faketouch</code></p>
 <ul>
 <li> MUST report the absolute X and Y screen positions of the pointer location and display a visual pointer on the screen [<a href="#resources80">Resources, 80</a>] </li>
 <li> MUST report touch event with the action code [<a href="#resources80">Resources, 80</a>] that specifies the state change
 that occurs on the pointer going <code>down</code> or <code>up</code> on the screen [<a href="#resources80">Resources, 80</a>] </li>
 <li> MUST support pointer <code>down</code> and <code>up</code> on an object on the screen, which allows users to emulate tap on an object on the screen</li>
 <li> MUST support pointer <code>down</code>, pointer <code>up</code>, pointer <code>down</code> then pointer <code>up</code> in the same place on an object on the screen
 within a time threshold, which allows users to emulate double tap on an object on the screen [<a href="#resources80">Resources, 80</a>]</li>
 <li>MUST support pointer <code>down</code> on an arbitrary point on the screen, pointer move to any other arbitrary point on the screen,
 followed by a pointer <code>up</code>, which allows users to emulate a touch drag</li>
 <li> MUST support pointer <code>down</code> then allow users to quickly move the object to a different position on the screen
 and then pointer <code>up</code> on the screen, which allows users to fling an object on the screen</li>
 </ul>

 <p>Devices that declare support for <code>android.hardware.faketouch.multitouch.distinct</code> MUST meet the requirements for
 faketouch above, and MUST also support distinct tracking of two or more independent pointer inputs.</p>

 <a name="section-7.2.6"></a><h4 id="section-7.2.6">7.2.6. Microphone</h4>
 <p>Device implementations MAY omit a microphone. However, if a device
 implementation omits a microphone, it MUST NOT report the
 <code>android.hardware.microphone</code> feature constant, and must implement
 the audio recording API as no-ops, per <a href="section-7">Section 7</a>.
 Conversely, device implementations that do possess a microphone:</p>
 <ul>
 <li>MUST report the <code>android.hardware.microphone</code> feature constant</li>
 <li>SHOULD meet the audio quality requirements in <a href="section-5.4">Section 5.4</a></li>
 <li>SHOULD meet the audio latency requirements in <a href="section-5.5">Section 5.5</a></li>
 </ul>

 <a name="section-7.3"></a><h3 id="section-7.3">7.3. Sensors</h3>
 <p>Android includes APIs for accessing a variety of sensor types. Devices
 implementations generally MAY omit these sensors, as provided for in the
 following subsections. If a device includes a particular sensor type that has a
 corresponding API for third-party developers, the device implementation MUST
 implement that API as described in the Android SDK documentation. For example,
 device implementations:</p>
 <ul>
 <li>MUST accurately report the presence or absence of sensors per the
 <code>android.content.pm.PackageManager</code> class. [<a
 href="#resources37">Resources, 37</a>]</li>
 <li>MUST return an accurate list of supported sensors via the
 <code>SensorManager.getSensorList()</code> and similar methods</li>
 <li>MUST behave reasonably for all other sensor APIs (for example, by
 returning true or false as appropriate when applications attempt to register
 listeners, not calling sensor listeners when the corresponding sensors are not
 present; etc.)</li>
 <li>MUST report all sensor measurements using the relevant International System
 of Units (i.e. metric) values for each sensor type as defined in the Android SDK
 documentation [<a href="#resources41">Resources, 41</a>]</li>
 </ul>
 <p>The list above is not comprehensive; the documented behavior of the Android
 SDK is to be considered authoritative.</p>
 <p>Some sensor types are synthetic, meaning they can be derived from data
 provided by one or more other sensors. (Examples include the orientation
 sensor, and the linear acceleration sensor.) Device implementations SHOULD
 implement these sensor types, when they include the prerequisite physical
 sensors.</p>
 <p>Android includes a notion of a "streaming" sensor, which is
 one that returns data continuously, rather than only when the data changes.
 Device implementations MUST continuously provide periodic data samples for any
 API indicated by the Android SDK documentation to be a streaming
 sensor. Note that the device implementations MUST ensure that the sensor stream must not
 prevent the device CPU from entering a suspend state or waking up from a suspend state.</p>

 <a name="section-7.3.1"></a><h4 id="section-7.3.1">7.3.1. Accelerometer</h4>
 <p>Device implementations SHOULD include a 3-axis accelerometer. If a device
 implementation does include a 3-axis accelerometer, it:</p>
 <ul>
 <li>SHOULD be able to deliver events at 120 Hz or greater. Note that while the
 accelerometer frequency above is stated as "SHOULD" for Android 4.4, the Compatibility Definition
 for a future version is planned to change these to "MUST". That is, these standards are
 optional in Android but <b>will be required</b> in future versions. Existing and
 new devices that run Android are <b>very strongly encouraged to meet these requirements
 in Android</b> so they will be able to upgrade to the future platform releases
 </li>
 <li>MUST comply with the Android sensor coordinate system as detailed
 in the Android APIs (see [<a href="#resources41">Resources, 41</a>])</li>
 <li>MUST be capable of measuring from freefall up to twice gravity (2g) or
 more on any three-dimensional vector</li>
 <li>MUST have 8-bits of accuracy or more</li>
 <li>MUST have a standard deviation no greater than 0.05 m/s^2</li>
 </ul>
 <a name="section-7.3.2"></a><h4 id="section-7.3.2">7.3.2. Magnetometer</h4>
 <p>Device implementations SHOULD include a 3-axis magnetometer (i.e. compass.)
 If a device does include a 3-axis magnetometer, it:</p>
 <ul>
 <li>MUST be able to deliver events at 10 Hz or greater</li>
 <li>MUST comply with the Android sensor coordinate system as detailed
 in the Android APIs (see [<a href="#resources41">Resources, 41</a>]).</li>
 <li>MUST be capable of sampling a range of field strengths adequate to cover the
 geomagnetic field</li>
 <li>MUST have 8-bits of accuracy or more</li>
 <li>MUST have a standard deviation no greater than 0.5 &micro;T</li>
 </ul>
 <a name="section-7.3.3"></a><h4 id="section-7.3.3">7.3.3. GPS</h4>
 <p>Device implementations SHOULD include a GPS receiver. If a device
 implementation does include a GPS receiver, it SHOULD include
 some form of "assisted GPS" technique to minimize GPS lock-on time.</p>
 <a name="section-7.3.4"></a><h4 id="section-7.3.4">7.3.4. Gyroscope</h4>
 <p>Device implementations SHOULD include a gyroscope (i.e. angular change
 sensor.) Devices SHOULD NOT include a gyroscope sensor unless a 3-axis
 accelerometer is also included. If a device implementation includes a
 gyroscope, it:</p>
 <ul>
 <li>MUST be temperature compensated.</li>
 <li>MUST be capable of measuring orientation changes up to 5.5*Pi
 radians/second (that is, approximately 1,000 degrees per second).</li>
 <li>SHOULD be able to deliver events at 200 Hz or greater. Note that while the
 gyroscope frequency above is stated as "SHOULD" for Android 4.4, the Compatibility Definition
 for a future version is planned to change these to "MUST". That is, these standards are
 optional in Android but <b>will be required</b> in future versions. Existing and
 new devices that run Android are <b>very strongly encouraged to meet these requirements</b>
 so they will be able to upgrade to the future platform releases.
 </li>
 <li>MUST have 12-bits of accuracy or more</li>
 <li>MUST have a variance no greater than 1e-7 rad^2 / s^2 per Hz (variance per Hz, or rad^2 / s).
 The variance is allowed to vary with the sampling rate, but must be constrained by this value.
 In other words, if you measure the variance of the gyro at 1 Hz sampling rate it should be no
 greater than 1e-7 rad^2/s^2.</li>
 <li>MUST have timestamps as close to when the hardware event happened as possible. The constant latency must be removed.</li>
 </ul>
 <a name="section-7.3.5"></a><h4 id="section-7.3.5">7.3.5. Barometer</h4>
 <p>Device implementations MAY include a barometer (i.e. ambient air pressure
 sensor.) If a device implementation includes a barometer, it:</p>
 <ul>
 <li>MUST be able to deliver events at 5 Hz or greater</li>
 <li>MUST have adequate precision to enable estimating altitude</li>
 <li>MUST be temperature compensated</li>
 </ul>
 <a name="section-7.3.6"></a><h4 id="section-7.3.6">7.3.6. Thermometer</h4>
 <p>Device implementations MAY include an ambient thermometer (i.e. temperature
 sensor). If present, it MUST be defined as <code>SENSOR_TYPE_AMBIENT_TEMPERATURE</code>
 and it MUST measure the ambient (room) temperature in degrees Celsius.</p>

 <p>Device implementations MAY but SHOULD NOT include a CPU temperature sensor.
 If present, it MUST be defined as <code>SENSOR_TYPE_TEMPERATURE</code>, it MUST
 measure the temperature of the device CPU, and it MUST NOT measure any other
 temperature. Note the <code>SENSOR_TYPE_TEMPERATURE</code> sensor type was
 deprecated in Android 4.0.</p>
 <a name="section-7.3.7"></a><h4 id="section-7.3.7">7.3.7. Photometer</h4>
 <p>Device implementations MAY include a photometer (i.e. ambient light
 sensor.)</p>
 <a name="section-7.3.8"></a><h4 id="section-7.3.8">7.3.8. Proximity Sensor</h4>
 <p>Device implementations MAY include a proximity sensor.  If a device
 implementation does include a proximity sensor, it MUST measure the proximity
 of an object in the same direction as the screen. That is, the proximity
 sensor MUST be oriented to detect objects close to the screen, as the
 primary intent of this sensor type is to detect a phone in use by the
 user. If a device implementation includes a proximity sensor with any other
 orientation, it MUST NOT be accessible through this API. If a device
 implementation has a proximity sensor, it MUST be have 1-bit of accuracy or
 more.</p>

 <a name="section-7.4"></a><h3 id="section-7.4">7.4. Data Connectivity</h3>
 <a name="section-7.4.1"></a><h4 id="section-7.4.1">7.4.1. Telephony</h4>
 <p>"Telephony" as used by the Android APIs and this document refers
 specifically to hardware related to placing voice calls and sending SMS
 messages via a GSM or CDMA network. While these voice calls may or may not be
 packet-switched, they are for the purposes of Android considered
 independent of any data connectivity that may be implemented using the same
 network. In other words, the Android "telephony" functionality and APIs refer
 specifically to voice calls and SMS; for instance, device implementations that
 cannot place calls or send/receive SMS messages MUST NOT report the
 "android.hardware.telephony" feature or any sub-features, regardless of
 whether they use a cellular network for data connectivity.</p>
 <p>Android MAY be used on devices that do not include telephony hardware.
 That is, Android is compatible with devices that are not phones.
 However, if a device implementation does include GSM or CDMA telephony, it
 MUST implement full support for the API for that technology. Device
 implementations that do not include telephony hardware MUST implement the full
 APIs as no-ops.</p>
 <a name="section-7.4.2"></a><h4 id="section-7.4.2">7.4.2. IEEE 802.11 (Wi-Fi)</h4>
 <p>Android device implementations SHOULD include support for one or more
 forms of 802.11 (b/g/a/n, etc.) If a device implementation does include
 support for 802.11, it MUST implement the corresponding Android API.</p>
 <p>Device implementations MUST implement the multicast API as described in
 the SDK documentation [<a href="#resources62">Resources, 62</a>]. Device
 implementations that do include Wi-Fi support MUST support multicast DNS (mDNS).
 Device implementations MUST NOT filter mDNS packets (224.0.0.251) at any time
 of operation including when the screen is not in an active state.</p>

 <a name="section-7.4.2.1"></a>
 <h4 id="section-7.4.2.1">7.4.2.1. Wi-Fi Direct</h4>
 <p>Device implementations SHOULD include support for Wi-Fi direct (Wi-Fi peer-to-peer).
 If a device implementation does include support for Wi-Fi direct, it MUST implement the corresponding
 Android API as described in the SDK documentation [<a href="#resources68">Resources, 68</a>].
 If a device implementation includes support for Wi-Fi direct, then it:</p>
 <ul>
   <li>MUST support regular Wi-Fi operation</li>
   <li>SHOULD support concurrent Wi-Fi and Wi-Fi Direct operation</li>
 </ul>

 <a name="section-7.4.2.2"></a><h4 id="section-7.4.2.2">7.4.2.2. Wi-Fi Tunneled Direct Link Setup</h4>
 <p>Device implementations SHOULD include support for Wi-Fi Tunneled Direct Link
 Setup (TDLS) as described in the Android SDK Documentation
 [<a href="#resources85">Resources, 85</a>]. If a device implementation does
 include support for TDLS and TDLS is enabled by the WiFiManager API, the device:
 </p>
 <ul>
   <li>SHOULD use TDLS only when it is possible AND beneficial.</li>
   <li>SHOULD have some heuristic and NOT use TDLS when its performance might be
   worse than going through the Wi-Fi access point.</li>
 </ul>

 <a name="section-7.4.3"></a><h4 id="section-7.4.3">7.4.3. Bluetooth</h4>
 <p>Device implementations SHOULD include a Bluetooth transceiver. Device
 implementations that do include a Bluetooth transceiver MUST enable the
 RFCOMM-based Bluetooth API as described in the SDK documentation and declare
 hardware feature android.hardware.bluetooth [<a href="#resources42">Resources, 42</a>].
 Device implementations SHOULD implement relevant Bluetooth profiles, such as A2DP, AVRCP, OBEX, etc. as
 appropriate for the device.</p>

 <p>Device implementations that do include support for Bluetooth GATT (generic attribute profile)
 to enable communication with Bluetooth Smart or Smart Ready devices MUST enable the
 GATT-based Bluetooth API as described in the SDK documentation and declare hardware feature
 android.hardware.bluetooth_le [<a href="#resources42">Resources, 42</a>].</p>

 <a name="section-7.4.4"></a><h4 id="section-7.4.4">7.4.4. Near-Field Communications</h4>
 <p>Device implementations SHOULD include a transceiver and related hardware
 for Near-Field Communications (NFC). If a device implementation does include
 NFC hardware, then it:</p>
 <ul>
   <li>MUST report the android.hardware.nfc feature from the
       <code>android.content.pm.PackageManager.hasSystemFeature()</code> method.
       [<a href="#resources37">Resources, 37</a>]</li>
   <li>MUST be capable of reading and writing NDEF messages via the following NFC
       standards:
    <ul>
     <li>MUST be capable of acting as an NFC Forum reader/writer
         (as defined by the NFC Forum technical specification
         NFCForum-TS-DigitalProtocol-1.0) via the following NFC standards:
      <ul>
       <li>NfcA (ISO14443-3A)</li>
       <li>NfcB (ISO14443-3B) </li>
       <li>NfcF (JIS 6319-4)</li>
       <li>IsoDep (ISO 14443-4)</li>
       <li>NFC Forum Tag Types 1, 2, 3, 4 (defined by the NFC Forum)</li>
      </ul>
     </li>
    </ul>
   </li>
   <li>SHOULD be capable of reading and writing NDEF messages via the following
       NFC standards. Note that while the NFC standards below are stated as
       "SHOULD", the Compatibility Definition for a future version is planned to
       change these to "MUST". That is, these standards are optional in this
       version but <b>will be required</b> in future versions. Existing and new
       devices that run this version of Android are <b>very strongly encouraged
       to meet these requirements now</b> so they will be able to upgrade to the
       future platform releases.
     <ul>
       <li>NfcV (ISO 15693)</li>
     </ul>
   </li>
   <li>MUST be capable of transmitting and receiving data via the following
       peer-to-peer standards and protocols:
     <ul>
       <li>ISO 18092</li>
       <li>LLCP 1.0 (defined by the NFC Forum)</li>
       <li>SDP 1.0 (defined by the NFC Forum)</li>
       <li>NDEF Push Protocol [<a href="#resources43">Resources, 43</a>]</li>
       <li>SNEP 1.0 (defined by the NFC Forum)</li>
     </ul>
   </li>
   <li>MUST include support for Android Beam [<a href="#resources65">Resources, 65</a>]:
    <ul>
     <li>MUST implement the SNEP default server. Valid NDEF messages received
         by the default SNEP server MUST be dispatched to applications using
         the android.nfc.ACTION_NDEF_DISCOVERED intent. Disabling Android Beam
         in settings MUST NOT disable dispatch of incoming NDEF message.</li>
     <li>Device implementations MUST honor the android.settings.NFCSHARING_SETTINGS intent
         to show NFC sharing settings [<a href="#resources67">Resources, 67</a>].</li>
     <li>MUST implement the NPP server. Messages received by the NPP server MUST
         be processed the same way as the SNEP default server.</li>
     <li>MUST implement a SNEP client and attempt to send outbound P2P NDEF to
         the default SNEP server when Android Beam is enabled. If no default
         SNEP server is found then the client MUST attempt to send to an NPP
         server.</li>
     <li>MUST allow foreground activities to set the outbound P2P NDEF message
         using android.nfc.NfcAdapter.setNdefPushMessage, and
         android.nfc.NfcAdapter.setNdefPushMessageCallback, and
         android.nfc.NfcAdapter.enableForegroundNdefPush.</li>
     <li>SHOULD use a gesture or on-screen confirmation, such as 'Touch to Beam',
         before sending outbound P2P NDEF messages.</li>
     <li>SHOULD enable Android Beam by default</li>
     <li>MUST support NFC Connection handover to Bluetooth when the device supports Bluetooth Object Push Profile.
         Device implementations must support connection handover to Bluetooth when using android.nfc.NfcAdapter.setBeamPushUris,
         by implementing the "Connection Handover version 1.2" [<a href="#resources60">Resources, 60</a>]
         and "Bluetooth Secure Simple Pairing Using NFC version 1.0" [<a href="#resources61">Resources, 61</a>]
         specs from the NFC Forum. Such an implementation MUST implement the
         handover LLCP service with service name "urn:nfc:sn:handover" for
         exchanging the handover request/select records over NFC, and it MUST use
         the Bluetooth Object Push Profile for the actual Bluetooth data
         transfer. For legacy reasons (to remain compatible with Android 4.1
         devices), the implementation SHOULD still accept SNEP GET requests for
         exchanging the handover request/select records over NFC. However an
         implementation itself SHOULD NOT send SNEP GET requests for performing
         connection handover.</li>
    </ul>
   </li>
   <li>MUST poll for all supported technologies while in NFC discovery mode.</li>
   <li>SHOULD be in NFC discovery mode while the device is awake with the screen active
       and the lock-screen unlocked.</li>
 </ul>

 <p>(Note that publicly available links are not available for the JIS, ISO, and
 NFC Forum specifications cited above.)</p>
 <p>Android 4.4 introduces support for NFC Host Card Emulation (HCE) mode. If a
 device implementation does include an NFC controller capable of HCE and
 Application ID (AID) routing, then it:</p>
 <ul>
   <li>MUST report the <code>android.hardware.nfc.hce</code> feature constant
   </li>
   <li>MUST support NFC HCE APIs as defined in the Android SDK
   [<a href="#resources90">Resources, 90</a>]</li>
 </ul>
 <p>Additionally, device implementations MAY include reader/writer support for
 the following MIFARE technologies.</p>
 <ul>
   <li>MIFARE Classic (NXP MF1S503x [<a href="#resources44">Resources, 44</a>],
       MF1S703x [<a href="#resources45">Resources, 45</a>])</li>
   <li>MIFARE Ultralight (NXP MF0ICU1 [<a href="#resources46">Resources, 46</a>],
       MF0ICU2 [<a href="#resources47">Resources, 47</a>])</li>
   <li>NDEF on MIFARE Classic (NXP AN130511 [<a href="#resources48">Resources, 48</a>],
       AN130411 [<a href="#resources49">Resources, 49</a>])</li>
 </ul>
 <p>Note that Android includes APIs for these MIFARE types. If a
 device implementation supports MIFARE in the reader/writer role, it:</p>
 <ul>
   <li>MUST implement the corresponding Android APIs as documented by the
   Android SDK</li>
   <li>MUST report the feature com.nxp.mifare from the
   <code>android.content.pm.PackageManager.hasSystemFeature()</code> method.
   [<a href="#resources37">Resources, 37</a>] Note that this is not a standard
   Android feature, and as such does not appear as a constant on the
   <code>PackageManager</code> class.</li>
   <li>MUST NOT implement the corresponding Android APIs nor report the
   com.nxp.mifare feature unless it also implements general NFC support as
   described in this section</li>
 </ul>
 <p>If a device implementation does not include NFC hardware, it MUST NOT
 declare the android.hardware.nfc feature from the
 <code>android.content.pm.PackageManager.hasSystemFeature()</code> method [<a
 href="#resources37">Resources, 37</a>], and MUST implement the Android NFC
 API as a no-op.</p>
 <p>As the classes <code>android.nfc.NdefMessage</code> and
 <code>android.nfc.NdefRecord</code> represent a protocol-independent data
 representation format, device implementations MUST implement these APIs even
 if they do not include support for NFC or declare the android.hardware.nfc
 feature.</p>
 <a name="section-7.4.5"></a><h4 id="section-7.4.5">7.4.5. Minimum Network Capability</h4>
 <p>Device implementations MUST include support for one or more forms of data
 networking. Specifically, device implementations MUST include support for at
 least one data standard capable of 200Kbit/sec or greater. Examples of
 technologies that satisfy this requirement include EDGE, HSPA, EV-DO, 802.11g,
 Ethernet, etc.</p>
 <p>Device implementations where a physical networking standard (such as
 Ethernet) is the primary data connection SHOULD also include support for at
 least one common wireless data standard, such as 802.11 (Wi-Fi).</p>
 <p>Devices MAY implement more than one form of data connectivity.</p>

 <a name="section-7.4.6"></a><h4 id="section-7.4.6">7.4.6. Sync Settings</h4>
 <p>Device implementations MUST have the master auto-sync setting on by default
 so that the method <code>getMasterSyncAutomatically()</code> returns
 &quot;true&quot; [<a href="#resources88">Resources, 88</a>].</p>

 <a name="section-7.5"></a><h3 id="section-7.5">7.5. Cameras</h3>
 <p>Device implementations SHOULD include a rear-facing camera, and MAY include
 a front-facing camera. A rear-facing camera is a camera located on the side of
 the device opposite the display; that is, it images scenes on the far side of
 the device, like a traditional camera. A front-facing camera is a camera
 located on the same side of the device as the display; that is, a camera
 typically used to image the user, such as for video conferencing and similar
 applications.</p>
 <a name="section-7.5.1"></a><h4 id="section-7.5.1">7.5.1. Rear-Facing Camera</h4>
 <p>Device implementations SHOULD include a rear-facing camera. If a device
 implementation includes a rear-facing camera, it:</p>
 <ul>
 <li>MUST have a resolution of at least 2 megapixels</li>
 <li>SHOULD have either hardware auto-focus, or software auto-focus implemented
 in the camera driver (transparent to application software)</li>
 <li>MAY have fixed-focus or EDOF (extended depth of field) hardware</li>
 <li>MAY include a flash. If the Camera includes a flash, the flash lamp MUST
 NOT be lit while an android.hardware.Camera.PreviewCallback instance has been
 registered on a Camera preview surface, unless the application has explicitly
 enabled the flash by enabling the <code>FLASH_MODE_AUTO</code> or
 <code>FLASH_MODE_ON</code> attributes of a <code>Camera.Parameters</code>
 object. Note that this constraint does not apply to the device's built-in
 system camera application, but only to third-party applications using
 <code>Camera.PreviewCallback</code>.</li>
 </ul>
 <a name="section-7.5.2"></a><h4 id="section-7.5.2">7.5.2. Front-Facing Camera</h4>
 <p>Device implementations MAY include a front-facing camera. If a device
 implementation includes a front-facing camera, it:</p>
 <ul>
 <li>MUST have a resolution of at least VGA (that is, 640x480 pixels)</li>
 <li>MUST NOT use a front-facing camera as the default for the Camera API.
 That is, the camera API in Android has specific support for front-facing
 cameras, and device implementations MUST NOT configure the API to to treat a
 front-facing camera as the default rear-facing camera, even if it is the only
 camera on the device.</li>
 <li>MAY include features (such as auto-focus, flash, etc.)
 available to rear-facing cameras as described in Section 7.5.1.</li>
 <li>MUST horizontally reflect (i.e. mirror) the stream displayed by an app in a
 CameraPreview, as follows:</li>
 <ul>
 <li>If the device implementation is capable of being rotated by user (such as
 automatically via an accelerometer or manually via user input), the camera
 preview MUST be mirrored horizontally relative to the device's current
 orientation.</li>
 <li>If the current application has explicitly requested that the Camera
 display be rotated via a call to the
 <code>android.hardware.Camera.setDisplayOrientation()</code> [<a
 href="#resources50">Resources, 50</a>] method, the camera preview MUST be
 mirrored horizontally relative to the orientation specified by the
 application.</li>
 <li>Otherwise, the preview MUST be mirrored along the device's default horizontal axis.</li>
 </ul>
 <li>MUST mirror the image displayed by the postview in the same manner as
 the camera preview image stream. (If the device implementation does not
 support postview, this requirement obviously does not apply.)</li>
 <li>MUST NOT mirror the final captured still image or video streams returned
 to application callbacks or committed to media storage</li>
 </ul>
 <a name="section-7.5.3"></a><h4 id="section-7.5.3">7.5.3. Camera API Behavior</h4>
 <p>Device implementations MUST implement the following behaviors for the
 camera-related APIs, for both front- and rear-facing cameras:</p>
 <ol>
 <li>If an application has never called
 <code>android.hardware.Camera.Parameters.setPreviewFormat(int)</code>, then the
 device MUST use <code>android.hardware.PixelFormat.YCbCr_420_SP</code> for
 preview data provided to application callbacks.</li>
 <li>If an application registers an <code>android.hardware.Camera.PreviewCallback
 </code> instance and the system calls the <code>onPreviewFrame()</code> method
 when the preview format is YCbCr_420_SP, the data in the <code>byte[]</code>
 passed into <code>onPreviewFrame()</code> must further be in the NV21 encoding
 format. That is, NV21 MUST be the default.</li>
 <li>Device implementations MUST support the YV12 format (as denoted by the
 <code>android.graphics.ImageFormat.YV12</code> constant) for camera previews
 for both front- and rear-facing cameras.  (The hardware video encoder and camera
 may use any native pixel format, but the device implementation MUST support conversion
 to YV12.)</li>
 </ol>
 <p>Device implementations MUST implement the full Camera API included in the
 Android SDK documentation [<a href="#resources51">Resources, 51</a>]),
 regardless of whether the device includes hardware autofocus or other
 capabilities. For instance, cameras that lack autofocus MUST still call any
 registered <code>android.hardware.Camera.AutoFocusCallback</code> instances (even though
 this has no relevance to a non-autofocus camera.) Note that this does apply
 to front-facing cameras; for instance, even though most front-facing cameras
 do not support autofocus, the API callbacks must still be "faked" as
 described.</p>
 <p>Device implementations MUST recognize and honor each parameter name defined
 as a constant on the <code>android.hardware.Camera.Parameters</code> class, if the
 underlying hardware supports the feature. If the device hardware does not
 support a feature, the API must behave as documented. Conversely, Device
 implementations MUST NOT honor or recognize string constants passed
 to the <code>android.hardware.Camera.setParameters()</code> method other than
 those documented as constants on the
 <code>android.hardware.Camera.Parameters</code>.  That is,
 device implementations MUST support all standard Camera parameters if the
 hardware allows, and MUST NOT support custom Camera parameter types.
 For instance, device implementations that support image capture using high dynamic range (HDR)
 imaging techniques MUST support camera parameter <code>Camera.SCENE_MODE_HDR</code>
 [<a href="#resources78">Resources, 78</a>]).</p>
 <p>Device implementations MUST broadcast the <code>Camera.ACTION_NEW_PICTURE</code>
 intent whenever a new picture is taken by the camera and the entry of the picture
 has been added to the media store.</p>
 <p>Device implementations MUST broadcast the <code>Camera.ACTION_NEW_VIDEO</code>
 intent whenever a new video is recorded by the camera and the entry of the picture
 has been added to the media store.</p>
 <a name="section-7.5.4"></a><h4 id="section-7.5.4">7.5.4. Camera Orientation</h4>
 <p>Both front- and rear-facing cameras, if present, MUST be oriented so that
 the long dimension of the camera aligns with the screen's long dimension. That
 is, when the device is held in the landscape orientation, cameras MUST
 capture images in the landscape orientation. This applies regardless of the
 device's natural orientation; that is, it applies to landscape-primary devices
 as well as portrait-primary devices.</p>

 <a name="section-7.6"></a><h3 id="section-7.6">7.6. Memory and Storage</h3>
 <a name="section-7.6.1"></a><h4 id="section-7.6.1">7.6.1. Minimum Memory and Storage</h4>
 <p>Device implementations MUST have at least 340MB of memory available to the
 kernel and userspace. The 340MB MUST be in addition to any memory dedicated to
 hardware components such as radio, video, and so on that is not under the
 kernel's control.</p>
 <p>Device implementations with less than 512MB of memory available to the kernel
 and userspace MUST return the value &quot;true&quot; for
 <code>ActivityManager.isLowRamDevice()</code>.</p>
 <p>Device implementations MUST have at least 1GB of non-volatile storage available
 for application private data. That is, the <code>/data</code> partition MUST be at
 least 1GB. Device implementations that run Android are <b>very strongly encouraged to
 have at least 2GB of non-volatile storage for application private data</b> so they will be
 able to upgrade to the future platform releases.</p>

 <p>The Android APIs include a Download Manager that applications may use to
 download data files [<a href="#resources56">Resources, 56</a>]. The device
 implementation of the Download Manager MUST be capable of downloading individual
 files of at least 100MB in size to the default "cache" location.</p>
 <a name="section-7.6.2"></a><h4 id="section-7.6.2">7.6.2. Shared External Storage</h4>
 <p>Device implementations MUST offer shared storage for applications. The
 shared storage provided MUST be at least 1GB in size.</p>
 <p>Device implementations MUST be configured with shared storage mounted by
 default, "out of the box". If the shared storage is not mounted on the Linux
 path <code>/sdcard</code>, then the device MUST include a Linux symbolic link
 from <code>/sdcard</code> to the actual mount point.</p>
 <p>Device implementations MUST enforce as documented the
 <code>android.permission.WRITE_EXTERNAL_STORAGE</code> permission on this
 shared storage. Shared storage MUST otherwise be writable by any application
 that obtains that permission.</p>
 <p>Device implementations MAY have hardware for user-accessible removable
 storage, such as a Secure Digital card. Alternatively, device implementations
 MAY allocate internal (non-removable) storage as shared storage for apps. The
 upstream Android Open Source Project includes an implementation that uses
 internal device storage for shared external storage APIs; device implementations
 SHOULD use this configuration and software implementation.</p>
 <p>Regardless of the form of shared storage used, device implementations MUST
 provide some mechanism to access the contents of shared storage from a host
 computer, such as USB mass storage (UMS) or Media Transfer Protocol (MTP). Device
 implementations MAY use USB mass storage, but SHOULD use Media Transfer
 Protocol. If the device implementation supports Media Transfer Protocol:</p>
 <ul>
 <li>The device implementation SHOULD be compatible with the reference Android
 MTP host, Android File Transfer [<a href="#resources57">Resources, 57</a>].</li>
 <li>The device implementation SHOULD report a USB device class of <code>0x00</code>.</li>
 <li>The device implementation SHOULD report a USB interface name of 'MTP'.</li>
 </ul>
 <p>If the device implementation lacks USB ports, it MUST provide a host
 computer with access to the contents of shared storage by some other means,
 such as a network file system.</p>
 <p>It is illustrative to consider two common examples. If a device
 implementation includes an SD card slot to satisfy the shared storage
 requirement, a FAT-formatted SD card 1GB in size or larger MUST be included
 with the device as sold to users, and MUST be mounted by default.
 Alternatively, if a device implementation uses internal fixed storage to
 satisfy this requirement, that storage MUST be 1GB in size or larger
 and mounted on <code>/sdcard</code> (or <code>/sdcard</code>
 MUST be a symbolic link to the physical location if it is mounted elsewhere.)</p>
 <p>Device implementations that include multiple shared storage paths (such as
 both an SD card slot and shared internal storage) MUST NOT allow Android
 applications to write to the secondary external storage, except for their
 package-specific directories on the secondary external storage, but SHOULD
 expose content from both storage paths transparently through Android's media
 scanner service and android.provider.MediaStore.</p>

 <a name="section-7.7"></a><h3 id="section-7.7">7.7. USB</h3>
 <p>Device implementations SHOULD include a USB client port, and SHOULD include
 a USB host port.</p>
 <p>If a device implementation includes a USB client port:</p>
 <ul>
 <li>the port MUST be connectable to a USB host with a standard USB-A port</li>
 <li>the port SHOULD use the micro USB form factor on the device side. Existing and
 new devices that run Android are <b>very strongly encouraged to meet these requirements
 in Android</b> so they will be able to upgrade to the future platform releases</li>
 <li>the port SHOULD be centered in the middle of an edge. Device implementations SHOULD either
 locate the port on the bottom of the device (according to natural orientation) or enable software
 screen rotation for all apps (including home screen), so that the display draws correctly when the device
 is oriented with the port at bottom. Existing and new devices that run Androidare <b>very strongly
 encouraged to meet these requirements in Android</b> so they will be able to upgrade to future platform releases.</li>
 <li>if the device has other ports (such as a non-USB charging port) it SHOULD be on the same edge as the
 micro-USB port</li>
 <li>it MUST allow a host connected to the device to access the contents of the
 shared storage volume using either USB mass storage or Media Transfer
 Protocol</li>
 <li>it MUST implement the Android Open Accessory API and specification as documented
 in the Android SDK documentation, and MUST declare support for the hardware
 feature <code>android.hardware.usb.accessory</code> [<a href="#resources52">Resources,
 52</a>]</li>
 <li>it MUST implement the USB audio class as documented in the Android SDK documentation [<a href="#resources66">Resources, 66</a>]</li>
 <li>it SHOULD implement support for USB battery charging specification [<a href="#resources64">Resources, 64</a>]
 Existing and new devices that run Android are <b>very strongly encouraged to
 meet these requirements</b>
 so they will be able to upgrade to the future platform releases</li>
 <li>The value of iSerialNumber in USB standard device descriptor MUST be equal to the value of android.os.Build.SERIAL.</li>
 </ul>
 <p>If a device implementation includes a USB host port:</p>
 <ul>
 <li>it MAY use a non-standard port form factor, but if so MUST ship with a
 cable or cables adapting the port to standard USB-A</li>
 <li>it MUST implement the Android USB host API as documented in the Android
 SDK, and MUST declare support for the hardware feature
 <code>android.hardware.usb.host</code> [<a href="#resources53">Resources, 53</a>]</li>
 </ul>
 <p>Device implementations MUST implement the Android Debug Bridge. If a device
 implementation omits a USB client port, it MUST implement the Android Debug
 Bridge via local-area network (such as Ethernet or 802.11)</p>

 <a name="section-8"></a><h2 id="section-8">8. Performance Compatibility</h2>
 <p>Device implementations MUST meet the key performance metrics of an Android-
 compatible device defined in the table below:</p>
 <table><tbody><tr>
 <td><b>Metric</b></td>
 <td><b>Performance Threshold</b></td>
 <td><b>Comments</b></td>
 </tr>
 <tr>
 <td>Application Launch Time</td>
 <td>The following applications should launch within the specified time.<ul>
 <li>Browser: less than 1300ms</li>
 <li>Contacts: less than 700ms</li>
 <li>Settings: less than 700ms</li>
 </ul></td>
 <td>The launch time is measured as the total time to
 complete loading the default activity for the application, including the time
 it takes to start the Linux process, load the Android package into the Dalvik
 VM, and call onCreate.</td>
 </tr>
 <tr>
 <td>Simultaneous Applications</td>
 <td>When multiple applications have been launched, re-launching an
 already-running application after it has been launched must take less than the
 original launch time.</td>
 <td>&nbsp;</td>
 </tr>
 </tbody>
 </table>

 <a name="section-9"></a><h2 id="section-9">9. Security Model Compatibility</h2>
 <p>Device implementations MUST implement a security model consistent with the
 Android platform security model as defined in Security and Permissions
 reference document in the APIs [<a href="#resources54">Resources, 54</a>] in the
 Android developer documentation. Device implementations MUST support
 installation of self-signed applications without requiring any additional
 permissions/certificates from any third parties/authorities.  Specifically,
 compatible devices MUST support the security mechanisms described in the
 follow sub-sections.</p>
 <a name="section-9.1"></a><h3 id="section-9.1">9.1. Permissions</h3>
 <p>Device implementations MUST support the Android permissions model as
 defined in the Android developer documentation [<a
 href="#resources54">Resources, 54</a>]. Specifically,
 implementations MUST enforce each permission defined as described in the SDK
 documentation; no permissions may be omitted, altered, or ignored.
 Implementations MAY add additional permissions, provided the new permission ID
 strings are not in the android.* namespace.</p>
 <a name="section-9.2"></a><h3 id="section-9.2">9.2. UID and Process Isolation</h3>
 <p>Device implementations MUST support the Android application sandbox model,
 in which each application runs as a unique Unix-style UID and in a separate
 process.  Device implementations MUST support running multiple applications as
 the same Linux user ID, provided that the applications are properly signed and
 constructed, as defined in the Security and Permissions reference [<a
 href="#resources54">Resources, 54</a>].</p>
 <a name="section-9.3"></a><h3 id="section-9.3">9.3. Filesystem Permissions</h3>
 <p>Device implementations MUST support the Android file access permissions
 model as defined in the Security and Permissions reference [<a
 href="#resources54">Resources, 54</a>].</p>
 <a name="section-9.4"></a><h3 id="section-9.4">9.4. Alternate Execution Environments</h3>
 <p>Device implementations MAY include runtime environments that execute
 applications using some other software or technology than the Dalvik virtual
 machine or native code. However, such alternate execution environments MUST
 NOT compromise the Android security model or the security of installed Android
 applications, as described in this section.</p>
 <p>Alternate runtimes MUST themselves be Android applications, and abide by
    the standard Android security model, as described elsewhere in Section 9.</p>
 <p>Alternate runtimes MUST NOT be granted access to resources protected by
    permissions not requested in the runtime's AndroidManifest.xml file via the
    <code>&lt;uses-permission&gt;</code> mechanism.</p>
 <p>Alternate runtimes MUST NOT permit applications to make use of features
    protected by Android permissions restricted to system applications.</p>
 <p>Alternate runtimes MUST abide by the Android sandbox model.  Specifically:</p>
 <ul>
 <li>Alternate runtimes SHOULD install apps via the PackageManager into
     separate Android sandboxes (that is, Linux user IDs, etc.)</li>
 <li>Alternate runtimes MAY provide a single Android sandbox shared by all
     applications using the alternate runtime</li>
 <li>Alternate runtimes and installed applications using an alternate runtime
     MUST NOT reuse the sandbox of any other app installed on the device, except
     through the standard Android mechanisms of shared user ID and signing
     certificate</li>
 <li>Alternate runtimes MUST NOT launch with, grant, or be granted access to
     the sandboxes corresponding to other Android applications</li>
 </ul>
 <p>Alternate runtimes MUST NOT be launched with, be granted, or grant to other
    applications any privileges of the superuser (root), or of any other user ID.</p>
 <p>The .apk files of alternate runtimes MAY be included in the system image of
    a device implementation, but MUST be signed with a key distinct
    from the key used to sign other applications included with the device
    implementation.</p>
 <p>When installing applications, alternate runtimes MUST obtain user consent
    for the Android permissions used by the application. That is, if an
    application needs to make use of a device resource for which there is a
    corresponding Android permission (such as Camera, GPS, etc.), the alternate
    runtime MUST inform the user that the application will be able to access
    that resource. If the runtime environment does not record application
    capabilities in this manner, the runtime environment MUST list all
    permissions held by the runtime itself when installing any application
    using that runtime.</p>

 <a name="section-9.5"></a><h3 id="section-9.5">9.5. Multi-User Support </h3>
 <p>Android includes support for multiple users and provides support for full user isolation
 [<a href="#resources70">Resources, 70</a>].</p>
 <p>Device implementations MUST meet these requirements related to multi-user support [<a href="#resources71">Resources, 71</a>]:</p>
 <ul>
 <li>As the behavior of the telephony APIs on devices with multiple users is currently undefined, device implementations that
 declare android.hardware.telephony MUST NOT enable multi-user support. </li>
 <li>Device implementations MUST, for each user, implement a security model consistent with the Android platform security model
 as defined in Security and Permissions reference document in the APIs [Resources, 54]</li>
 <li>Android includes support for restricted profiles, a feature that allows device owners to manage additional users and their capabilities
 on the device. With restricted profiles, device owners can quickly set up separate environments for additional users to work in, with the ability to
 manage finer-grained restrictions in the apps that are available in those environments. Device implementations that include support for multiple users
 MUST include support for restricted profiles. The upstream Android Open Source Project includes an implementation that satisfies this requirement.</li>
 </ul>

 <p>Each user instance on an Android device MUST have separate and isolated external storage directories. Device implementations MAY store multiple users' data on the same volume or filesystem.
 However, the device implementation MUST ensure that applications owned by and running on behalf a given user cannot list, read, or write to data owned by any other user.
 Note that removable media, such as SD card slots, can allow one user to access another's data by means of a host PC. For this reason, device implementations that use removable media for the
 external storage APIs MUST encrypt the contents of the SD card if multi-user is enabled using a key stored only on non-removable media accessible only to the system. As this will make the
 media unreadable by a host PC, device implementations will be required to switch to MTP or a similar system to provide host PCs with access to the current user's data. Accordingly, device
 implementations MAY but SHOULD NOT enable multi-user if they use removable media [<a href="#resources72">Resources, 72</a>] for primary external storage.</p>

 <a name="section-9.6"></a><h3 id="section-9.6">9.6. Premium SMS Warning</h3>
 <p>Android includes support for warning users for any outgoing premium SMS message [<a href="#resources73">Resources, 73</a>] . Premium SMS messages are text messages sent to a service registered with a carrier that may incur a charge to the user.
 Device implementations that declare support for <code>android.hardware.telephony</code> MUST warn users before sending a SMS message to numbers identified by regular expressions defined in <code>/data/misc/sms/codes.xml</code> file in the device.
 The upstream Android Open Source Project provides an implementation that satisfies this requirement.
 </p>

 <a name="section-9.7"></a><h3 id="section-9.7">9.7. Kernel Security Features</h3>
 <p>The Android Sandbox includes features that can use the Security-Enhanced
 Linux (SELinux) mandatory access control (MAC) system and other security
 features in the Linux kernel. SELinux or any other security features, if
 implemented below the Android framework:</p>
 <ul>
 <li>MUST maintain compatibility with existing applications</li>
 <li>MUST not have a visible user interface, even when violations are detected
 </li>
 <li>SHOULD NOT be user or developer configurable</li>
 </ul>
 <p>If any API for configuration of policy is exposed to an application that can
 affect another application (such as a Device Administration API), the API MUST
 NOT allow configurations that break compatibility.</p>
 <p>Devices MUST implement SELinux and meet the following requirements, which
 are satisfied by the reference implementation in the upstream Android Open
 Source Project.</p>
 <ul>
 <li>it MUST support a SELinux policy that allows the SELinux mode to be set on
 a per-domain basis with:</li>
 <ul>
   <li>domains that are in enforcing mode in the upstream Android Open Source
   implementation (such as installd, netd, and vold) MUST be in enforcing mode
   </li>
   <li>domain(s) for third-party applications SHOULD remain in permissive mode to
    ensure continued compatibility</li>
 </ul>
 <li>it SHOULD load policy from <code>/sepolicy</code> file on the device</li>
 <li>it MUST support dynamic updates of the SELinux policy file without requiring
 a system image update</li>
 <li>it MUST log any policy violations without breaking applications or affecting
 system behavior</li>
 </ul>

 <p>Device implementations SHOULD retain the default SELinux policy provided in
 the upstream Android Open Source Project, until they have first audited their
 additions to the SELinux policy. Device implementations MUST be compatible with
 the upstream Android Open Source Project.</p>

 <a name="section-9.8"></a><h3 id="section-9.8">9.8. Privacy</h3>
 <p>If the device implements functionality in the system that captures the
 contents displayed on the screen and/or records the audio stream played on the
 device, it MUST continuously notify the user whenever this functionality is
 enabled and actively capturing/recording.</p>

 <a name="section-9.9"></a><h3 id="section-9.9">9.9. Full-Disk Encryption</h3>
 <p>IF the device has lockscreen, the device MUST support full-disk
 encryption.</p>

 <a name="section-10"></a><h2 id="section-10">10. Software Compatibility Testing</h2>
 <p>Device implementations MUST pass all tests described in this section.</p>
 <p>However, note that no software test package is fully comprehensive. For
 this reason, device implementers are very strongly encouraged to make the
 minimum number of changes as possible to the reference and preferred
 implementation of Android available from the Android Open Source Project.
 This will minimize the risk of introducing bugs that create incompatibilities
 requiring rework and potential device updates.</p>
 <a name="section-10.1"></a><h3 id="section-10.1">10.1. Compatibility Test Suite</h3>
 <p>Device implementations MUST pass the Android Compatibility Test Suite (CTS)
 [<a href="#resources02">Resources, 2</a>] available from the Android Open Source
 Project, using the final shipping software on the device. Additionally, device
 implementers SHOULD use the reference implementation in the Android Open
 Source tree as much as possible, and MUST ensure compatibility in cases of
 ambiguity in CTS and for any reimplementations of parts of the reference
 source code.</p>
 <p>The CTS is designed to be run on an actual device. Like any software, the
 CTS may itself contain bugs.  The CTS will be versioned independently of this
 Compatibility Definition, and multiple revisions of the CTS may be released
 for Android 4.4. Device implementations MUST pass the latest CTS version
 available at the time the device software is completed.</p>
 <a name="section-10.2"></a><h3 id="section-10.2">10.2. CTS Verifier</h3>
 <p>Device implementations MUST correctly execute all applicable cases in the
 CTS Verifier. The CTS Verifier is included with the Compatibility Test Suite,
 and is intended to be run by a human operator to test functionality that
 cannot be tested by an automated system, such as correct functioning of a
 camera and sensors.</p>
 <p>The CTS Verifier has tests for many kinds of hardware, including some
 hardware that is optional. Device implementations MUST pass all tests for
 hardware which they possess; for instance, if a device possesses an
 accelerometer, it MUST correctly execute the Accelerometer test case in the
 CTS Verifier. Test cases for features noted as optional by this Compatibility
 Definition Document MAY be skipped or omitted.</p>
 <p>Every device and every build MUST correctly run the CTS Verifier, as noted
 above. However, since many builds are very similar, device implementers are
 not expected to explicitly run the CTS Verifier on builds that differ only in
 trivial ways. Specifically, device implementations that differ from an
 implementation that has passed the CTS Verifier only by the set of included
 locales, branding, etc. MAY omit the CTS Verifier test.</p>
 <a name="section-10.3"></a><h3 id="section-10.3">10.3. Reference Applications</h3>
 <p>Device implementers MUST test implementation compatibility using the
 following open source applications:</p>
 <ul>
 <li>The "Apps for Android" applications [<a href="#resources55">Resources, 55</a>]</li>
 <li>Replica Island (available in Google Play Store)</li>
 </ul>
 <p>Each app above MUST launch and behave correctly on the implementation, for
 the implementation to be considered compatible.</p>


 <a name="section-11"></a><h2 id="section-11">11. Updatable Software</h2>
 <p>Device implementations MUST include a mechanism to replace the entirety of
 the system software. The mechanism need not perform "live" upgrades - that
 is, a device restart MAY be required.</p>
 <p>Any method can be used, provided that it can replace the entirety of the
 software preinstalled on the device. For instance, any of the following
 approaches will satisfy this requirement:</p>
 <ul>
 <li>Over-the-air (OTA) downloads with offline update via reboot</li>
 <li>"Tethered" updates over USB from a host PC</li>
 <li>"Offline" updates via a reboot and update from a file on removable
 storage</li>
 </ul>
 <p>The update mechanism used MUST support updates without wiping user data.
 That is, the update mechanism MUST preserve application private data
 and application shared data. Note that the upstream Android software includes
 an update mechanism that satisfies this requirement.</p>
 <p>If an error is found in a device implementation after it has been released
 but within its reasonable product lifetime that is determined in consultation
 with the Android Compatibility Team to affect the compatibility of third-party
 applications, the device implementer MUST correct the error via a software
 update available that can be applied per the mechanism just described.</p>

 <a name="section-12"></a><h2 id="section-12">12. Document Changelog</h2>
 <p>The following table contains a summary of the changes to the Compatibility Definition in this release.</p>
 <table width="100%" border="1">
   <tr>
     <th width="25%" scope="col">Section(s)</th>
     <th width="75%" scope="col">Summary of change</th>
   </tr>
   <tr>
     <td>3.2.2. Build Parameters</td>
     <td>Revised descriptions of BRAND, DEVICE, and PRODUCT. SERIAL is now
 required.</td>
   </tr>
   <tr>
     <td>3.2.3.5. Default App Settings</td>
     <td>New section that adds requirement to comply with new default
     application settings</td>
   </tr>
   <tr>
     <td>3.3.1 Application Binary Interfaces</td>
     <td>Clarified allowed values for the <code>android.os.Build.CPU_ABI</code>
      and <code>android.os.Build.CPU_ABI2</code> parameters.</td>
   </tr>
   <tr>
     <td>3.4.1. WebView Compatibility</td>
     <td>Added Chromium as required WebView implementation.</td>
   </tr>
   <tr>
     <td>3.7. Virtual Machine Compatibility</td>
     <td>Added requirement for xxhdpi and 400dpi screen densities.</td>
   </tr>
   <tr>
     <td>3.8.6. Themes</td>
     <td>Updated to reflect use of translucent system bars.</td>
   </tr>
   <tr>
     <td>3.8.12. Location</td>
     <td>New section that adds requirement location settings be centralized.</td>
   </tr>
   <tr>
     <td>3.8.13. Unicode</td>
     <td>New section that adds requirement for emoji support.</td>
   </tr>
   <tr>
     <td>3.9. Device Administration</td>
     <td>Noted preinstalled administrative applications cannot be the default
      Device Owner application.</td>
   </tr>
   <tr>
     <td>5.1. Media Codecs</td>
     <td>Added VP9 decoder requirement. Added recommended specification for
      hardware VP8 codecs.</td>
   </tr>
   <tr>
     <td>5.3. Video Decoding</td>
     <td>Added VP9. Added recommendation for dynamic resolution switching.</td>
   </tr>
   <tr>
     <td>5.4. Audio Recording</td>
     <td>Added <code>REMOTE_SUBMIX</code> as new required audio source. Made use
      of <code>android.media.audiofx.NoiseSuppressor</code> API a requirement.</td>
   </tr>
   <tr>
     <td>6.2.1 Experimental</td>
     <td>New section that introduces the ART runtime and requires Dalvik as the
       default runtime.</td>
   </tr>
   <tr>
     <td>7.1.1. Screen Configuration</td>
     <td>Replaced 1.85 aspect ratio with 1.86. Added 400dpi screen density.</td>
   </tr>
   <tr>
     <td>7.1.6. Screen Types</td>
     <td>Added 640 dpi (4K) resolution configuration.</td>
   </tr>
   <tr>
     <td>7.2.3. Navigation keys</td>
     <td>Added Recents function as essential; demoted Menu function in priority.</td>
   </tr>
   <tr>
     <td>7.3.6. Thermometer</td>
     <td>Added SENSOR_TYPE_AMBIENT_TEMPERATURE as recommended thermometer.</td>
   </tr>
   <tr>
     <td>7.4.2.2. Wi-Fi Tunneled Direct Link Setup</td>
     <td>New section that adds support for Wi-Fi Tunneled Direct Link Setup
      (TDLS).</td>
   </tr>
   <tr>
     <td>7.4.4. Near-Field Communications</td>
     <td>Added Host Card Emulation (HCE) as a requirement. Replaced SNEP GET with
      Logical Link Control Protocol (LLCP) and added the Bluetooth Object Push
      Profile as a requirement.</td>
   </tr>
   <tr>
     <td>7.4.6. Sync Settings</td>
     <td>New section that adds requirement auto-sync data be enabled by default.</td>
   </tr>
   <tr>
     <td>7.6.1. Minimum Memory and Storage</td>
     <td>Added <code>ActivityManager.isLowRamDevice()</code> setting requirement
     for devices with less than 512MB of memory. Increased storage requirements
     from 512MB and 1GB to 1GB and 2GB, respectively.</td>
   </tr>
   <tr>
     <td>7.6.2. Shared "External" Storage</td>
     <td>Editorial fixes such as change of section name, and moved text that fits
      in this section from section 9.5. Noted applications may write to their
      package-specific directories on secondary external storage.</td>
   </tr>
   <tr>
     <td>7.7. USB</td>
     <td>Added requirement all devices report a USB serial number.</td>
   </tr>
   <tr>
     <td>9.5. Multi-User Support</td>
     <td>Moved non multi-user specific text to  section 7.6.2.</td>
   </tr>
   <tr>
     <td>9.7. Kernel Security Features</td>
     <td>Rewritten to note switch of SELinux to enforcing mode and requirement
      SELinux output not be rendered in the user interface.</td>
   </tr>
   <tr>
     <td>9.8. Privacy</td>
     <td>New section that adds requirement audio and video recording must trigger
      continuous notifications to the user.</td>
   </tr>
   <tr>
     <td>9.9. Full-Disk Encryption</td>
     <td>New section that adds requirement devices with lockscreen support full-disk encryption.</td>
   </tr>
   <tr>
     <td>12. Document Changelog</td>
     <td>New section that summarizes changes in the CDD by section.</td>
   </tr>
 </table>
 <p>&nbsp;</p>

 <a name="section-13"></a><h2 id="section-13">13. Contact Us</h2>
 <p>You can contact the document authors at <a
 href="mailto:compatibility@android.com">compatibility@android.com</a> for
 clarifications and to bring up any issues that you think the document does not
 cover.</p>

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