Compatibility Definition

MAY omit a non-touch navigation option (trackball, d-pad, or wheel) if the device
implementation is not an Android Television device.
MUST report the correct value for android.content.res.Configuration.navigation
[Resources, 85].
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.
7.2.3. Navigation Keys
The availability and visibility requirement of the Home, Recents, and Back functions differ
between device types as described in this section.
The Home, Recents, and Back functions (mapped to the key events KEYCODE_HOME,
KEYCODE_APP_SWITCH, KEYCODE_BACK, respectively) are essential to the Android navigation
paradigm and therefore:
Android Handheld device implementations MUST provide the Home, Recents, and Back
functions.
Android Television device implementations MUST provide the Home and Back functions.
Android Watch device implementations MUST have the Home function available to the
user, and the Back function except for when it is in UI_MODE_TYPE_WATCH.
Android Automotive implementations MUST provide the Home function and MAY provide
Back and Recent functions.
All other types of device implementations MUST provide the Home and Back functions.
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.
Recents function, if provided, MUST have a visible button or icon unless hidden together with other
navigation functions in full-screen mode. This does not apply to devices upgrading from earlier
Android versions that have physical buttons for navigation and no recents key.
The Home and Back functions, if provided, MUST each have a visible button or icon unless hidden
together with other navigation functions in full-screen mode or when the uiMode
UI_MODE_TYPE_MASK is set to UI_MODE_TYPE_WATCH.
The Menu function is deprecated in favor of action bar since Android 4.0. Therefore the new device
implementations shipping with Android 6.0 and later MUST NOT implement a dedicated physical
button for the Menu function. Older device implementations SHOULD NOT implement a dedicated
physical button for the Menu function, but if the physical Menu button is implemented and the device is
running applications with targetSdkVersion > 10, the device implementation:
MUST display the action overflow button on the action bar when it is visible and the
resulting action overflow menu popup is not empty. For a device implementation launched
before Android 4.4 but upgrading to Android 6.0, this is RECOMMENDED.
MUST NOT modify the position of the action overflow popup displayed by selecting the
overflow button in the action bar.
MAY render the action overflow popup at a modified position on the screen when it is
displayed by selecting the physical menu button.
For backwards compatibility, device implementations MUST make the Menu function available to
applications when targetSdkVersion is less than 10, either by a physical button, a software key, or
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