This routine reads a parameter and attempt to open an NDF. If it fails it searches the directory DATADIR and then opens an NDF there. If that fails it asks again. This routine also recognises the SCUBA_PREFIX environment variable. When a number is given it is expanded to 4 digites (leading zeroes) and prepended with SCUBA_PREFIX and ’_dem_’ before opening the file. The priority is:

• File specified in current directory

• Check if filename was a number and look in current directory then either

• Look for full filename in DATADIR or

• Look for numbered name in DATADIR Only one of the last two will happen since I will know from the status return of CHR_CTOI whether a number was given.

CALL SCULIB_SEARCH_DATADIR(PACKAGE, PARAM, INDF, STATUS)

PACKAGE = CHAR (Given)

PARAM = CHAR (Given)

INDF = INTEGER (Returned)

STATUS = INTEGER (Given and Returned)

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• Uses some non PSX calls for accessing Current working directory These are GETCWD and CHDIR. This may be a portability issue.

• Checks for PAR__ABORT or PAR__NULL status from parameter.