manifest package

 http://www.android-doc.com/guide/topics/manifest/manifest-intro.html

• It names the Java package for the application. The package name serves as a unique identifier for the application.

However, as a shorthand, if the first character of the string is a period, the string is appended to the application's package name (as specified by the <manifest> element's package attribute). The following assignment is the same as the one above: 

<manifest package="com.example.project" . . . >
    <application . . . >
        <service android:name=".SecretService" . . . >
            . . .
        </service>
        . . .
    </application>
</manifest>

When starting a component, Android creates an instance of the named subclass. If a subclass isn't specified, it creates an instance of the base class.