[MIcroStation in general] Legal Chacters in Model, Level and other Object Names

I searched MicroStation help in vain for an answer to this question: What are the  legal (and illegal) characters for the names of Models, Levels, Item Types, etc.?

For example, I can create a model name such as Hyphenated-Model-Name, but not ModelName?.  That is, a hyphen is a legal character but question mark is an illegal character.  What other characters are illegal in a name?  Where are those documented?