The repository contains collections of downloadable packages. An SDK platform package. An SDK add-on package. An SDK tool package. An SDK doc package. An SDK extra package. This kind of package is for "free" content and specifies in which fixed root directory it must be installed. The paths "add-ons", "platforms", "tools" and "docs" are reserved and cannot be used. 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 SHA1 checksum. A file checksum, currently only SHA1.