f77 interprets VMS logical file names on the INCLUDE statement if:
The -xl[d] or -vax=spec compiler options are set.
The environment variable LOGICALNAMEMAPPING is there to define the mapping between the logical names and the UNIX path name.
f77 uses the following rules for the interpretation:
"lname1=path1; lname2=path2; "
where each lname is a logical name and each path1, path2, and so forth is the path name of a directory (without a trailing /).
All blanks are ignored when parsing this string. It strips any trailing /[no]list from the file name in the INCLUDE statement.
Logical names in a file name are delimited by the first : in the VMS file name, so f77 converts file names of the lname1:file form to the path1/file form.
For logical names, uppercase and lowercase are significant. If a logical name is encountered on the INCLUDE statement which is not specified in the LOGICALNAMEMAPPING, the file name is used, unchanged.