Creating an attribute with non-ASCII (special/foreign) characters like German Umlaut (e.g. "ö", "ä", "ü") will return the following error:
Error on saving changes:
Illegal attribute name value. Names can only contain alphanumeric
characters and must begin with upper case alphabetic character.
That happens from the version 2016.1 and on.
This is working as designed. Special characters will no longer be allowed in the NAME value of an Attribute or Object