The repository contains a collection of downloadable packages. An SDK add-on package. Version information for a layoutlib included in an addon. . An SDK extra package. This kind of package is for "free" content. Such packages are installed in SDK/vendor/path. One path segment for the install path of an extra element. It must be a single-segment path. It must not be empty. A semi-colon separated list of a segmentTypes. A license definition. Such a license must be used later as a reference using a uses-license element in one of the package elements. Describes the license used by a package. The license MUST be defined using a license node and referenced using the ref attribute of the license element inside a package. A collection of files that can be downloaded for a given architecture. The <archives> node is mandatory in the repository packages and the collection must have at least one <archive> declared. Each archive is a zip file that will be unzipped in a location that depends on its package type. A collection of file paths available in an <extra> package that can be installed in an Android project. If present, the <project-files> collection must contain at least one path. Each path is relative to the root directory of the package. A SHA1 checksum. A file checksum, currently only SHA1.