Username Character Limits

1) Length of String Limit

Ie: Username can be set to..

‘What Is The Character And Symbol Limits On Usernames?What Is The Character And Symbol Limits On Usernames?What Is The Character And Symbol Limits On Usernames?’

which is visually too long and does not display correctly in the UI (there are probably other reasons why you would want to avoid this beyond UI, for example 1) user experience [other users] and 2) storage concerns )

2) Character set (I only tried ‘?’ but if there is not a limit on use of special characters that would be recommended, I will try again later with other symbols)