Hi Matthias, congratulation for this release !
In the upstream-metadata project (https://wiki.debian.org/UpstreamMetadata) we document some information, some of which is redundant with what is now found in AppStream, and some of which is not. For example, we document bibliographic reference to the scientific litterature where a given sofwtware has been published. This particular data has been the driving need behind the creation of upstream-metadata project. But the moment, I do not have enough free time to take care of the upstream-metadata project properly. Given that the scope of AppStream has grown, do you think that it could be further extended to support the kind of information that we distribute in the debian/upstream/metadata files ? Have a nice day, (Please Cc me, I am not subscribed). — Charles