http://dacxzjk3kq5mmepbdd3ai2ifynlzxsnpl2cnkfhridqfywihrfftapid.onion/help/user/reserved_names.md
Rules for usernames, project and group names, and slugs
Usernames must start and end with a letter ( a-zA-Z ) or a digit ( 0-9 ).
For example, the following usernames satisfy these criteria:
A_Garcia
a_garcia_1
Additionally, usernames and group names must contain only letters ( a-zA-Z ), digits ( 0-9 ), emoji, underscores ( _ ), dots ( . ), parentheses ( () ), dashes ( - ), or spaces.