AppStream makes machine-readable software metadata easily accessible. It is a foundational block for modern Linux software centers, offering a seamless way to retrieve information about available software, no matter the repository it is contained in. It can provide data about available applications as well as available firmware, drivers, fonts and other components. This project it part of freedesktop.org.
Ask why. Then probably work on subversion… because it is seriously doubtful they’ve come back for any good reason.