src/source/build-numbers.md

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# Codenames, Tags, and Build Numbers #

At a high level, Android development happens around families of
releases, which use code names ordered alphabetically after tasty
treats.

The code names match the following version numbers, along with
API levels and NDK releases provided for convenience:

Code name      | Version | API level
---------------|---------|------------
(no code name) | 1.0     | API level 1
(no code name) | 1.1     | API level 2
Cupcake        | 1.5     | API level 3, NDK 1
Donut          | 1.6     | API level 4, NDK 2
Eclair         | 2.0     | API level 5
Eclair         | 2.0.1   | API level 6
Eclair         | 2.1     | API level 7, NDK 3
Froyo          | 2.2.x   | API level 8, NDK 4
Gingerbread    | 2.3.x   | API level 9, NDK 5

Starting with Cupcake, individual builds are identified with a short
build code, e.g. FRF85B. The first letter is the code name of the
release family, e.g. F is Froyo. The second letter is a branch code
that allows Google to identify the exact code branch that the build
was made from, and R is by convention the primary release branch.
The next letter and two digits are a date code. The letter counts
quarters, with A being Q1 2009. Therefore, F is Q2 2010. The two
digits count days within the quarter, so F85 is June 24 2010.
Finally, the last letter identifies individual versions related to
the same date code, sequentially starting with A; A is actually
implicit and usually omitted for brevity. The date code is not
guaranteed to be the exact date at which a build was made, and it is
common that minor variations added to an existing build re-use the
same date code as that existing build.

Starting with Donut, the exact list of tags and builds is in the
following table:

Build  | Tag                | Notes
-------|--------------------|-----------------------------------
DRC83  | android-1.6_r1.1     earliest Donut version, ADP1, ADP2
DRC92  | android-1.6_r1.2
DRD08  | android-1.6_r1.3
DRD20  | android-1.6_r1.4
DMD64  | android-1.6_r1.5   | latest Donut version
ESD20  | android-2.0_r1     | earliest Eclair version
ESD56  | android-2.0.1_r1
ERD79  | android-2.1_r1     | Nexus One
ERE27  | android-2.1_r2     | Nexus One
EPE54B | android-2.1_r2.1p  | Nexus One
ESE81  | android-2.1_r2.1s
EPF21B | android-2.1_r2.1p2 | latest Eclair version
FRF85B | android-2.2_r1     | earliest Froyo version, Nexus One
FRF91  | android-2.2_r1.1   | Nexus One
FRG01B | android-2.2_r1.2
FRG22D | android-2.2_r1.3
FRG83  | android-2.2.1_r1   | Nexus One
FRG83D | android-2.2.1_r2   | Nexus One
FRG83G | android-2.2.2_r1   | latest Froyo version, Nexus One
GRH55  | android-2.3_r1     | earliest Gingerbread version, Nexus S
GRH78  | android-2.3.1_r1   | Nexus S
GRH78C | android-2.3.2_r1   | latest Gingerbread version, Nexus S

The branches donut, eclair, froyo, gingerbread represent development
branches that do not exactly match configurations that were tested
by Google. They might contain a variety of changes in addition to
the official tagged releases, and those haven't been as thoroughly
tested.