I am making a form for Greek users. There is a field (containing a code) which has to be filled in with only latin characters.
Now, most letters in the Greek alphabet look the same as their Latin counterparts, however they are completely different ASCII characters. Users are inclined to start typing in Greek and, after they notice they are using the wrong keyboard layout, they switch to English and continue typing. This way, different codes are typed, although they look the same.
Is there a way to limit input to latin characters and exclude non-latin characters? I have tried to specify the character code in pattern fields. This can limit the characters to A-Z but it does not prohibit non-latin characters.