@evan @jonny @steve Well, no, 'ap' stands for Activity Pub. FEP-ef61 is not a different protocol, it only adds new features to the existing one. Furthermore, these features can be implemented in backward compatible way (@nomad can confirm).
The URI scheme is not set in stone, however. I agree that this is not a standard way to retrieve objects, and there might be other practical reasons to use a different scheme. I think it can be changed to 'nomad' as @django suggested, or perhaps to 'ap+nomad' or something like that.