NDF_ASSOC( PARAM, MODE, INDF, STATUS )
-- Associate an existing NDF with an ADAM parameter
NDF_EXIST( PARAM, MODE, INDF, STATUS )
-- See if an existing NDF is associated with an ADAM parameter.
NDF_FIND( LOC, NAME, INDF, STATUS )
-- Find an NDF in an HDS structure and import it into the NDF_ system
NDF_OPEN( LOC, NAME, MODE, STAT, INDF, PLACE, STATUS )
-- Open an existing or new NDF