CLIC\DIRECTORY [filespec]
Build a directory listing and store it into SIC variables. If "filespec"
is omitted, the default pattern is "*.hpb".
The following SIC variables are defined (overwriting any previous val-
ues):
DIRLE Number of files found
DIRLE(1:DIRLE) File names
If "filespec" contains a SIC logical name followed by ':', the logical
is expanded before listing the files.