On Unix, the multi-line parameter help system uses the Starlink Portable HELP System (see
SUN/124). If the specified file name has no extension or extension .shl or .hlb, .shl is assumed;
anything else is an error.
On VMS, either Portable HELP or the VMS help system may be used. If the given filename has
extension .shl, Portable HELP is used: if no file extension, or .hlb, is specified, the system
will first look for a file with the given filename and extension .shl. If the file is found it
will be used with the Portable Help System. In all other cases, the VMS help system is
used.
In the interests of allowing the same Interface Modules to work on both VMS and Unix, both systems will handle names starting with (or wholly) environment variables (logical names) in either system’s style.
E.g.
$environment_variable/relative_pathname
or
logical_name:filename