...
Notes
If the filename cannot be reproduced in the space available, ie. C(in), then on exit C =1, B = 0 and the expansion buffer (stream or filter) will be given a NULL. Setting C(in) = 18 will guarantee the return of a filename and extension.
Bugs
If the source is in segment 2 then problems may occur.
Related calls
GN_Esa, read & write to filename segments
GN_Fex, expand a filename
GN_Opw, Open wildcard handler
GN_Pfs, parse filename segment
GN_Prs, parse filename
GN_Wcl, close wildcard handle
GN_Wfn, fetch next match for wildcard string (handle)
GN_Wsm, match filename segment to wildcard string