while talking about making a flickr plugin, we realised that we needed a bit smarter handling of supported formats. In this case, we would want to make it so that the caller could say it supported FORMAT_IMAGE and the fact that a portfolio plugin said FORMAT_FILE would mean a match.

Nico suggested doing a bitmask test on it but that doesn't work, because FORMAT_IMAGE < FORMAT_FILE, but not the other way around.

I am going to experiment with using actual php style inheritance and see if that sorts it.