? - Invokes the IDL Online Help facility when entered at the IDL command line.
DOC_LIBRARY - Extracts documentation headers from IDL programs.
HELP - Provides information about the current IDL session.
MEMORY - Returns information about dynamic memory currently in use by the IDL session.
MK_HTML_HELP - Converts text documentation headers to HTML files.
ONLINE_HELP - Invokes online help viewer from programs.
STRUCT_HIDE - Prevents the IDL HELP procedure from displaying information about structures or objects.