The PSF system associates a dataset with a PSF using one of the two routines PSF_ASSOCI, PSF_ASSOCO, depending on whether read or write access is being performed. Both routines return a PSF reference number to the application, which should be declared as type INTEGER. All subsequent access to PSF system routines should pass this reference number as the first argument. More than one PSF can be associated with the same dataset, and more than one dataset can be associated simultaneously. The total number of active references is defined by the symbolic constant PSF_NMAX in the ASTERIX include file PSF_PAR.
Before discussion of the routines which return useful data, the routine PSF_RELEASE should be mentioned. This simply frees all internal storage used by the PSF system for a specified reference.