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<action>

syntax:
<action android:name="string" />
contained in:
<intent-filter>

description:
Adds an action to an intent filter. An <intent-filter> element must contain one or more <action> elements. If there are no <action> elements in an intent filter, the filter doesn't accept any Intent objects. See Intents and Intent Filters for details on intent filters and the role of action specifications within a filter.
attributes:
android:name
The name of the action. Some standard actions are defined in the Intent class as ACTION_string constants. To assign one of these actions to this attribute, prepend "android.intent.action." to the string that follows ACTION_. For example, for ACTION_MAIN, use "android.intent.action.MAIN" and for ACTION_WEB_SEARCH, use "android.intent.action.WEB_SEARCH".

For actions you define, it's best to use your app's package name as a prefix to ensure uniqueness. For example, a TRANSMOGRIFY action might be specified as follows: 

<action android:name="com.example.project.TRANSMOGRIFY" />
introduced in:
API Level 1
see also:
<intent-filter>