For compatibility with FFREAD 1.0 - do not use

CALL FFREAD (NKEY, KEY, LOCVAR, LENVAR)

This is the old-fashioned form of using FFREAD and is only supplied for backward compatibility.

If NKEY is set to 0, it is used to modify the values for the default input/output LUNs.

If NKEY is negative, it will return them.

If NKEY is positive, it specifies the number of keys in KEY. The keys will be set up (destroying any previously defined keys) and FFGO called to do the work.

The arguments and their meaning:

NKEY

number of keys. Different actions depending on sign of NKEYS are described above.

KEY

array containing user's keys, one per machine word, with four significant characters.

LOCVAR

locations of variables/arrays to change as returned by LOCF dimensioned to NKEY).

LENVAR

length of array at location given in LOCVAR (dimensioned to NKEY).