The repository contains a collection of downloadable system images. System Image for a platform. Indicates a system-image is tied to an add-on and which one (the combo tag-id + vendor-id uniquely identifies the add-on.) Mandatory for add-on system-images. Must not be present for platform system-images. An tag string for a system image can only be simple alphanumeric string. The ABI of a platform's system image. 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 CPU bit size filter. A host OS filter. A JVM version number, e.g. "1" or "1.6" or "1.14.15". A SHA1 checksum. A file checksum, currently only SHA1.