## 3.2\. Soft API Compatibility
In addition to the managed APIs from [section 3.1](#3_1_managed_api_compatibility),
Android also includes a significant runtime-only “soft” API, in the form of such
things as intents, permissions, and similar aspects of Android applications that
cannot be enforced at application compile time.
### 3.2.1\. Permissions
* [C-0-1] Device implementers MUST support and enforce all permission
constants as documented by the [Permission reference page](http://developer.android.com/reference/android/Manifest.permission.html).
Note that [section 9](#9_security_model_compatibility) lists additional
requirements related to the Android security model.
### 3.2.2\. Build Parameters
The Android APIs include a number of constants on the
[android.os.Build class](http://developer.android.com/reference/android/os/Build.html)
that are intended to describe the current device.
* [C-0-1] 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.
<table>
<tr>
<th>Parameter</th>
<th>Details</th>
</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="http://source.android.com/compatibility/ANDROID_VERSION/versions.html">ANDROID_VERSION</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 ANDROID_VERSION,
this field MUST have the integer value ANDROID_VERSION_INT.</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 ANDROID_VERSION,
this field MUST have the integer value ANDROID_VERSION_INT.</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 reused 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 “^[a-zA-Z0-9_-]+$”.</td>
</tr>
<tr>
<td>BRAND</td>
<td>A value reflecting the brand name associated with the device as known to
the end users. MUST be in human-readable format and SHOULD represent the
manufacturer of the device or the company brand under which the device is
marketed. The value of this field MUST be encodable as 7-bit ASCII and match
the regular expression “^[a-zA-Z0-9_-]+$”.</td>
</tr>
<tr>
<td>SUPPORTED_ABIS</td>
<td>The name of the instruction set (CPU type + ABI convention) of native
code. See <a href="#3_3_native_api_compatibility">section 3.3. Native API
Compatibility</a>.</td>
</tr>
<tr>
<td>SUPPORTED_32_BIT_ABIS</td>
<td>The name of the instruction set (CPU type + ABI convention) of native
code. See <a href="#3_3_native_api_compatibility">section 3.3. Native API
Compatibility</a>.</td>
</tr>
<tr>
<td>SUPPORTED_64_BIT_ABIS</td>
<td>The name of the second instruction set (CPU type + ABI convention) of
native code. See <a href="#3_3_native_api_compatibility">section 3.3. Native
API Compatibility</a>.</td>
</tr>
<tr>
<td>CPU_ABI</td>
<td>The name of the instruction set (CPU type + ABI convention) of native
code. See <a href="#3_3_native_api_compatibility">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="#3_3_native_api_compatibility">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
“^[a-zA-Z0-9_-]+$”. This device name MUST NOT change during the
lifetime of the product.</td>
</tr>
<tr>
<td>FINGERPRINT</td>
<td>A string that uniquely identifies this build. It SHOULD be reasonably
human-readable. It MUST follow this template:
<p class="small">$(BRAND)/$(PRODUCT)/<br>
$(DEVICE):$(VERSION.RELEASE)/$(ID)/$(VERSION.INCREMENTAL):$(TYPE)/$(TAGS)</p>
<p>For example:</p>
<p class="small">acme/myproduct/<br>
mydevice:ANDROID_VERSION/LMYXX/3359:userdebug/test-keys</p>
<p>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.</p></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
“^[a-zA-Z0-9_-]+$”.</td>
</tr>
<tr>
<td>HOST</td>
<td>A string that uniquely identifies the host the build was built on, in
human-readable format. There are no requirements on the specific format of
this field, except that it MUST NOT be null or the empty string ("").</td>
</tr>
<tr>
<td>ID</td>
<td>An identifier chosen by the device implementer to refer to a specific
release, in human-readable format. This field can be the same as
android.os.Build.VERSION.INCREMENTAL, but SHOULD be a value sufficiently
meaningful for end users to distinguish between software builds. The value
of this field MUST be encodable as 7-bit ASCII and match the regular
expression “^[a-zA-Z0-9._-]+$”.</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 (""). This field
MUST NOT change during the lifetime of the product.</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 (""). This field MUST NOT change during the
lifetime of the product.</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 MUST 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 “^[a-zA-Z0-9_-]+$”. This product
name MUST NOT change during the lifetime of the product.</td>
</tr>
<tr>
<td>SERIAL</td>
<td>A hardware serial number, which MUST be available and unique across
devices with the same MODEL and MANUFACTURER. The value of this field MUST
be encodable as 7-bit ASCII and match the regular expression
“^([a-zA-Z0-9]{6,20})$”.</td>
</tr>
<tr>
<td>TAGS</td>
<td>A comma-separated list of tags chosen by the device implementer that
further distinguishes the build. This field MUST have one of the values
corresponding to the three typical Android platform signing configurations:
release-keys, dev-keys, test-keys.</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 MUST have one of the values
corresponding to the three typical Android runtime configurations: user,
userdebug, or eng.</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>
<tr>
<td>SECURITY_PATCH</td>
<td>A value indicating the security patch level of a build. It MUST signify
that the build is not in any way vulnerable to any of the issues described
up through the designated Android Public Security Bulletin. It MUST be in
the format [YYYY-MM-DD], matching a defined string documented in the
<a href="source.android.com/security/bulletin"> Android Public Security
Bulletin</a> or in the <a href="http://source.android.com/security/advisory">
Android Security Advisory</a>, for example "2015-11-01".</td>
</tr>
<tr>
<td>BASE_OS</td>
<td>A value representing the FINGERPRINT parameter of the build that is
otherwise identical to this build except for the patches provided in the
Android Public Security Bulletin. It MUST report the correct value and if
such a build does not exist, report an empty string ("").</td>
</tr>
<tr>
<td><a href="https://developer.android.com/reference/android/os/Build.html#BOOTLOADER">BOOTLOADER</a></td>
<td> A value chosen by the device implementer identifying the specific
internal bootloader version used in the device, in human-readable format.
The value of this field MUST be encodable as 7-bit ASCII and match the
regular expression “^[a-zA-Z0-9._-]+$”.</td>
</tr>
<tr>
<td><a href="https://developer.android.com/reference/android/os/Build.html#getRadioVersion()">getRadioVersion()</a></td>
<td> MUST (be or return) a value chosen by the device implementer
identifying the specific internal radio/modem version used in the device,
in human-readable format. If a device does not have any internal
radio/modem it MUST return NULL. The value of this field MUST be
encodable as 7-bit ASCII and match the regular expression
“^[a-zA-Z0-9._-,]+$”.</td>
</tr>
</table>
### 3.2.3\. Intent Compatibility
#### 3.2.3.1\. Core Application Intents
Android intents allow application components to request functionality from
other Android components. The Android upstream project includes a list of
applications considered core Android applications, which implements several
intent patterns to perform common actions.
* [C-0-1] Device implementations MUST preload one or more applications or
service components with an intent handler, for all the public intent filter
patterns defined by the following core android applications in AOSP:
* Desk Clock
* Browser
* Calendar
* Contacts
* Gallery
* GlobalSearch
* Launcher
* Music
* Settings
#### 3.2.3.2\. Intent Resolution
* [C-0-1] As Android is an extensible platform, device implementations MUST
allow each intent pattern referenced in [section 3.2.3.1](#3_2_3_1_core_application_intents)
to be overridden by third-party applications. The upstream Android open source
implementation allows this by default.
* [C-0-2] Dvice 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 that all
handle the same intent pattern.
* [C-0-3] Device implementations MUST provide a user interface for users to
modify the default activity for intents.
* However, device implementations MAY provide default activities for specific
URI patterns (e.g. http://play.google.com) when the default activity provides a
more specific attribute for the data URI. For example, an intent filter pattern
specifying the data URI “http://www.android.com” is more specific than the
browser's core intent pattern for “http://”.
Android also includes a mechanism for third-party apps to declare an
authoritative default [app linking behavior](https://developer.android.com/training/app-links)
for certain types of web URI intents. When such authoritative declarations are
defined in an app's intent filter patterns, device implementations:
* [C-0-4] MUST attempt to validate any intent filters by performing the
validation steps defined in the [Digital Asset Links specification](https://developers.google.com/digital-asset-links)
as implemented by the Package Manager in the upstream Android Open Source
Project.
* [C-0-5] MUST attempt validation of the intent filters during the installation of
the application and set all successfully validated URI intent filters as
default app handlers for their URIs.
* MAY set specific URI intent filters as default app handlers for their URIs,
if they are successfully verified but other candidate URI filters fail
verification. If a device implementation does this, it MUST provide the
user appropriate per-URI pattern overrides in the settings menu.
* MUST provide the user with per-app App Links controls in Settings as
follows:
* [C-0-6] The user MUST be able to override holistically the default app
links behavior for an app to be: always open, always ask, or never open,
which must apply to all candidate URI intent filters equally.
* [C-0-7] The user MUST be able to see a list of the candidate URI intent
filters.
* The device implementation MAY provide the user with the ability to
override specific candidate URI intent filters that were successfully
verified, on a per-intent filter basis.
* [C-0-8] The device implementation MUST provide users with the ability to
view and override specific candidate URI intent filters if the device
implementation lets some candidate URI intent filters succeed
verification while some others can fail.
#### 3.2.3.3\. Intent Namespaces
* [C-0-1] 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.
* [C-0-2] 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.
* [C-0-3] Device implementers MUST NOT alter or extend any of the intent
patterns used by the core apps listed in [section 3.2.3.1](#3_2_3_1_core_application_intents).
* Device implementations MAY include intent patterns using namespaces clearly
and obviously associated with their own organization. This prohibition is
analogous to that specified for Java language classes in [section 3.6](#3_6_api_namespaces).
#### 3.2.3.4\. Broadcast Intents
Third-party applications rely on the platform to broadcast certain intents to
notify them of changes in the hardware or software environment.
Device implementations:
* [C-0-1] MUST broadcast the public broadcast intents in response to
appropriate system events as described in the SDK documentation. Note that
this requirement is not conflicting with section 3.5 as the limitation for
background applications are also described in the SDK documentation.
#### 3.2.3.5\. Default App Settings
Android includes settings that provide users an easy way to select their
default applications, for example for Home screen or SMS.
Where it makes sense, device implementations MUST provide a similar settings
menu and be compatible with the intent filter pattern and API methods described
in the SDK documentation as below.
If device implementations report `android.software.home_screen`, they:
* [C-1-1] MUST honor the [`android.settings.HOME_SETTINGS`](
http://developer.android.com/reference/android/provider/Settings.html#ACTION_HOME_SETTINGS)
intent to show a default app settings menu for Home Screen.
If device implementations report `android.hardware.telephony`, they:
* [C-2-1] MUST provide a settings menu that will call the
[`android.provider.Telephony.ACTION_CHANGE_DEFAULT`](
http://developer.android.com/reference/android/provider/Telephony.Sms.Intents.html)
intent to show a dialog to change the default SMS application.
* [C-2-2] MUST honor the [`android.telecom.action.CHANGE_DEFAULT_DIALER`](
https://developer.android.com/reference/android/telecom/TelecomManager.html#ACTION_CHANGE_DEFAULT_DIALER)
intent to show a dialog to allow the user to change the default Phone
application.
* [C-2-3] MUST honor the [android.telecom.action.CHANGE_PHONE_ACCOUNTS](
https://developer.android.com/reference/android/telecom/TelecomManager.html#ACTION_CHANGE_PHONE_ACCOUNTS)
intent to provide user affordance to configure the [`ConnectionServices`](
https://developer.android.com/reference/android/telecom/ConnectionService.html)
associated with the [`PhoneAccounts`](
https://developer.android.com/reference/android/telecom/PhoneAccount.html), as
well as a default PhoneAccount that the telecommunications service provider will
use to place outgoing calls. The AOSP implementation meets this requirement by
including a "Calling Accounts option" menu within the "Calls" settings menu.
If device implementations report `android.hardware.nfc.hce`, they:
* [C-3-1] MUST honor the [android.settings.NFC_PAYMENT_SETTINGS](
http://developer.android.com/reference/android/provider/Settings.html#ACTION_NFC_PAYMENT_SETTINGS)
intent to show a default app settings menu for Tap and Pay.
If device implementations support the `VoiceInteractionService` and have more
than one application using this API installed at a time, they:
* [C-4-1] MUST honor the [`android.settings.ACTION_VOICE_INPUT_SETTINGS`](
https://developer.android.com/reference/android/provider/Settings.html#ACTION_VOICE_INPUT_SETTINGS)
intent to show a default app settings menu for voice input and assist.
### 3.2.4\. Activities on secondary displays
If device implementations allow launching normal [Android Activities](
https://developer.android.com/reference/android/app/Activity.html) on secondary
displays, they:
* [C-1-1] MUST set the `android.software.activities_on_secondary_displays`
feature flag.
* [C-1-2] MUST guarantee API compatibility similar to an activity running on
the primary display.
* [C-1-3] MUST land the new activity on the same display as the activity that
launched it, when the new activity is launched without specifying a target
display via the [`ActivityOptions.setLaunchDisplayId()`](
https://developer.android.com/reference/android/app/ActivityOptions.html#setLaunchDisplayId%28int%29)
API.
* [C-1-4] MUST destory all activities, when a display with the
[`Display.FLAG_PRIVATE`](http://developer.android.com/reference/android/view/Display.html#FLAG_PRIVATE)
flag is removed.
* [C-1-5] MUST resize accordingly all activities on a [`VirtualDisplay`](
https://developer.android.com/reference/android/hardware/display/VirtualDisplay.html)
if the display itself is resized.
* MAY show an IME (input method editor, a user control that enables users to
enter text) on the primary display, when a text input field becomes focused
on a secondary display.
* SHOULD implement the input focus on the secondary display independently of
the primary display, when touch or key inputs are supported.
* SHOULD have [`android.content.res.Configuration`](
https://developer.android.com/reference/android/content/res/Configuration.html)
which corresponds to that display in order to be displayed, operate
correctly, and maintain compatibility if an activity is launched on
secondary display.
If device implementations allow launching normal [Android Activities](
https://developer.android.com/reference/android/app/Activity.html) on secondary
displays and primary and secondary displays have different
[android.util.DisplayMetrics](https://developer.android.com/reference/android/util/DisplayMetrics.html):
* [C-2-1] Non-resizeable activities (that have `resizeableActivity=false` in
`AndroidManifest.xml`) and apps targeting API level 23 or lower MUST NOT be
allowed on secondary displays.
If device implementations allow launching normal [Android Activities](
https://developer.android.com/reference/android/app/Activity.html) on secondary
displays and a secondary display has the [android.view.Display.FLAG_PRIVATE](
https://developer.android.com/reference/android/view/Display.html#FLAG_PRIVATE)
flag:
* [C-3-1] Only the owner of that display, system, and activities that are
already on that display MUST be able to launch to it. Everyone can launch to
a display that has [android.view.Display.FLAG_PUBLIC](https://developer.android.com/reference/android/view/Display.html#FLAG_PUBLIC)
flag.