On 05/01/2016 05:50 AM, Ned Slider wrote: > > > On 01/05/16 13:23, Alice Wonder wrote: >> On 05/01/2016 05:10 AM, Alice Wonder wrote: >>> >>> I think this is my autism coming in to play, I think what is very clear >>> to me I just am not able to adequately communicate because clearly >>> people are not even remotely grasping what I am trying to convey. >>> >> >> Basically whether it is a white list or a black list doesn't matter. >> >> One is just the complement set of the other. >> >> It's the set I'm after. Or its complement. I don't care. Not whether my >> code should use set A or its complement. >> > > See Gordon's previous answer above: > > That is, [A-Za-z0-9._][A-Za-z0-9._-] > > In other words, allowable characters are A-Za-z (upper and lower case), > 0-9 (numerics), . and _ (period and underscore). > > Hyphens are allowed, but NOT as the first character, so maybe easier to > just not allow hyphens in your account usernames. > > > Well that excludes ' and I've seen ' (and even ’) in things like John.O'neill at example.org - I don't see a need to exclude those (or UTF8 above U+007F that non-western people often use) - which is kind of why I was hoping for a blacklist, characters that should be excluded. As fas a - and . that may not be at the beginning of a username (or two+ consecutive .) etc. - of course after checking for characters that are not allowed, the final address would have to go through a validator.