Android XML. What is the purpose of the star in the ID string?

In some sources I see such declarations

<item
    android:id="@+id/menu_display_groups"
    android:icon="@*android:drawable/ic_menu_allfriends"
    android:title="@string/menu_displayGroup" />

Notice the *

@*android:

It seems to give access to interna开发者_C百科l resources. But would like to know for sure.

Also curious, if it is safe to build application with such declarations using Android 2.2 SDK, and run it on 1.5.

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You are correct, it gives access to internal resources for platform apps. It is NOT safe to build apps with such declarations unless you are building a bundled app within a full system image.

Internal resources can (and do) change/get removed not only from platform version to platform version, but also from device to device or device version to device version.