Hmm, it was always defined in arc.arc, so I think it's intended for more than urls. Besides, why would bang be part of URL syntax? And wouldn't it also need ampersand? The original version seemed to include the characters for regular english punctuation.
Update an hour later: but I see where you're coming from; punc is only used in one function -- urlend.
Update two hours later: I found one regression in urlend: https://github.com/nex3/arc/commit/671c5ec916. We also have unit tests for markdown now, so any further regressions need only be caught once more.
