The TABULAR and RESPFILE options do not create PSFs but are methods which allow access to PSFs which have been previously created.
The TABULAR option reads in a single PSF from a datafile which has been created by the crepsf application. This option is useful when working with extended sources.
The RESPFILE option is an attempt to increase the processing speed in a PSF program by allowing access to a SPATIAL RESPONSE which is attached to the datafile. The spatial response is an ``array of PSF arrays.'' A spatial response is included in a datafile as a precomputed grid of point spread functions tailored to both the spatial and energy sub-space occupied by a dataset.
If a dataset repeatedly uses a PSF the program spresp can be used to create a PSF SPatial RESPonse and attach it to the dataset where it can be recalled as required. Because a SPATIAL RESPONSE is precalculated it also speeds processing time. This option is most useful in applications which make very intensive use of the PSF. Attaching a spatial response increase the size of a dataset.