This subroutine returns an NDF identifier for an image. This identifier may be passed to subroutines from the NDF library (see SUN/33) to perform lower-level operations on the data which cannot be done using IMG subroutines.

CALL IMG_INDF( PARAM, INDF, STATUS )

PARAM = CHARACTER $\ast$ ( $\ast$ ) (Given)

INDF = INTEGER (Returned)

STATUS = INTEGER (Given and Returned)

• The NDF identifier returned by this subroutine should be annulled (e.g. using NDF_ANNUL) when it is no longer required. The IMG system will not perform this operation itself.

• If this subroutine is called with STATUS set, then a value of NDF__NOID will be returned for the INDF argument, although no further processing will occur. The same value will also be returned if the subroutine should fail for any reason. The NDF__NOID constant is defined in the NDF_PAR include file.