It's mostly a question of how common they are. Both uuid and ISBN can be represented as URI. However, I'm still on the fence regarding uuids, because they tend

It's mostly a question of how common they are. Both uuid and ISBN can be represented as URI. However, I'm still on the fence regarding uuids, because they tend to get a lot of use in general... I may add it after all. The idea is to make a format for the 80% case, so things like ISBN are definitely out.