I am writing a program which will be testing to see if a file is a member
of a fileset.  To keep it simple, I'm starting with only MPE-syntax
files/filesets and I am accepting only the "@", "?" and "#" non-file-name
characters in the fileset (so no ranges of characters).

Is there an existing callable library routine which would make this
determination?  If not, does anyone have pseudo-code which might guide me?
The only problem I see at the moment is handling multiple commercial at
signs (@) in a given portion of a fileset; such as: myfile.a@[log in to unmask]

Just to make it a little trickier, this is a Cobol program, so recursion is
out for any inline code.