tools/aapt2/data/res/values/styles.xml

<?xml version="1.0" encoding="utf-8"?>
<resources xmlns:lib="http://schemas.android.com/apk/res/android.appcompat">
    <style name="App" parent="android.appcompat:Platform.AppCompat">
        <item name="android:background">@color/primary</item>
        <item name="android:colorPrimary">@color/primary</item>
        <item name="android:colorPrimaryDark">@color/primary_dark</item>
        <item name="android:colorAccent">@color/accent</item>
    </style>
    <attr name="custom" format="reference" />
    <style name="Pop">
        <item name="custom">@drawable/image</item>
        <item name="android:focusable">@lib:bool/allow</item>
    </style>
    <string name="yo">@string/wow</string>

    <declare-styleable name="View">
        <attr name="custom" />
        <attr name="decor">
            <enum name="no-border" value="0"/>
            <enum name="border" value="1"/>
            <enum name="shadow" value="2"/>
        </attr>
    </declare-styleable>

</resources>