It is possible to link an application to an external native library, or framework, by using the addExtraLibs ant task. This task may be used in _defaults_.xml, or the individual handset targets themselves. For the element <addExtraLibs> setting the platform attribute is mandatory. Inside this tag, libraries can be defined using the <library> tag. A name attribute is mandatory, and points to the name of the library or framework to be used. It must end with the correct file extension: .framework for a framework, .dylib for a dynamic library, and .a for a static library.