Code completion in drawable1.xml for <item ^></item>:
android:left : Left coordinate of the layer.  [dimension]
android:top : Top coordinate of the layer.  [dimension]
android:right : Right coordinate of the layer.  [dimension]
android:bottom : Bottom coordinate of the layer.  [dimension]
android:drawable : Drawable used to render the layer.  [reference]
android:id : Identifier of the layer.  [reference]