Form field validations - character set

[lausianne]

Hi,

A client asked me to prevent chinese characters to be sent in his forms. With RSForm this is simple, it offers a validation "letters" where chinese characters do not count as letters. So there will be an error message, when chinese (or japanese etc.) characters are entered.
Is there a (reasonably easy) way to achive this in VM forms?

Thanks!


EDIT: It's not that easy in RSForm, actually, because it won't accept many European language characters either (öäüßè etc.)