(I'll take this opportunity to repeat an earlier bikeshed of mine, which is that IPv6 address syntax should have used hyphens instead of colons, and dealt with

(I'll take this opportunity to repeat an earlier bikeshed of mine, which is that IPv6 address syntax should have used hyphens instead of colons, and dealt with the ensuing "is it a hostname or ip address?" problem by always requiring square brackets: [abcd-ef01--2345] C'est la vie.)