Allow Underscores at the start and end of Usernames
37
Regular Expression for alphanumeric and underscores
4511
What characters are allowed in the HTML Name attribute inside input tag?
2542
What should the character limit(s) for first/last name inputs be?
157628
Autocomplete username references in answer posts
30206
Where and how is the _ (underscore) variable specified?
134993
My name includes space - How do I enter my username when typing command?
122215
regex for Twitter username
33666
How do I change my Minecraft username during the 30-day restriction?
135805
Can we restrict the ability of users to keep changing their names?
91286
Tag name overflow on "top tags" section of user profile if tag name is long
61769
Support anchor names in posts
100787
How do I remove all specific characters at the end of a string in PHP?
144982
Certain usernames not displaying at all
2419
SQL Server Escape an Underscore
146492
How use spaces instead of underscores in file names?
42657
How do I remove the little × that shows up in the frontend when typing?
49988
Underscore in bibtex url