Exclude/accept only certain characters into a writeable icon.
When the system alphabet is UTF8 this validation command accepts multi-byte characters.
A[char list][~exclusion list] |
Allow characters in char list |
Disallow characters in exclusion list |
A0-9a-z~b |
Allows 0..9, a, c..z |
A~X |
Allows all chars but X |
A~\~ |
Allows all chars but ~ |
A~ |
Allows all chars |