Admin can set characters sets for registration
Admin can set characters sets which users can use in their names during registration

To provide administrators with option to set, which characters set can users use in their UserNames.

For example:
English one:
qwertyuiopasdfghjklzxcvbnm
QWERTYUIOPASDFGHJKLZXCVBNM
or
Russian one:
éöóêåíãøùçõúôûâàïðîëäæýÿ÷ñìèòüáþ¸
ÉÖÓÊÅÍÃØÙÇÕÚÔÛÂÀÏÐÎËÄÆÝß×ÑÌÈÒÜÁÞ¨
or
Numbers:
1234567890

In other words - admins can fill special field with all characters which users can use in their UserNames during registration.

P.S. Thanks Brandon Farber for helping!

Not a problem, and while this is a bit excessive, I do think a lot of admins might find thise useful.

I actually just had to code a custom request that only allowed a-zA-Z0-9 and space character in registration names. I'm sure others would find this sort of feature useful too.

I agree with you, that on those forums where admins use only Western character set - it will not be useful.
But on those forums where admins have to disable a setting in the ACP that allows you to strip these blank
characters - it will be very useful!!!

I had a correspondence with Brandon Farber about ASCII character (chr 173) - 'hidden' space.

Look at the picture and I think you will understand why I am asking for this future!