[BlueOnyx:22312] Acceptable characters in passwords

[Ernie]

Hi,
I have a 5209R server which has stopped a user logging in with a password
that has been ok for years, ftp login ore fine, it's just into the web GUI
that fails.

When I test the original password by trying to enter it as a password
change, it fails and an error about illegal characters appears.

What characters are illegal in passwords nowadays?
When did it change?

- Ernie.