The Red Hat manual is not too clear about this
IdM supports user names that can be described by the following regular
User names ending with the trailing dollar sign ($) are supported to
enable Samba 3.x machine support.
If you add a user whose user name contains uppercase characters, IdM
automatically converts the name to lowercase when saving it. Therefore,
IdM always requires users to enter their user names all lowercase when
logging in. Additionally, it is not possible to add users whose user
names only differ in letter casing, such as user and User.
Having co-workers from different countries using different languages we
want to avoid "strange" character from Cyrilic, German, Hindoi etc. etc.
Reading the docs, it suggest only plain UTF ASCII is supported, no
"strange" characters. Correct? Or else: how to avoid/not allow non
standard ASCII usernames?