I think it would be in bad form to restrict by protocol. If I invent httpplus next week my schema should not restrict me from using it. But that might be out of scope. Not only do we need both, I'm going to argue that we should be allowed to specify both for the same user-defined data type.
Pictures are nice and simple.
Regexps are powerful. One feature that pictures support that regexps do not is nice, guided editing. A regexp cannot. Of course the input would have to match both. If not, get rid of it.