Use the Filters page of the Options dialog to specify the filters used in such commands as File > Open > Model.
These characters are used by filters to reduce lists so they show only the files similar to the one(s) you are looking for.
The default wild card characters are the same as used by UNIX operating systems, but if you want to change them, just click in the text box and type a new character.
If you regularly use the same filter string, this option saves the need to retype it each time.