The visibility data is a an explicit function of time, baseline length, and frequency. Implicitly however, it is a function of many other parameters like the antenna co-ordinates, the RA, Dec of the fringe stopping center, local sidereal time (LST), compensating delays applied to the various antenna for fringe stopping etc. One would like to be able to extract any of these parameters from the database. Also, since the visibility is a complex function, one may like to extract the data in (Re,Im) or (Amp,Phs) format.
Since the combination of parameters and the format in which they can be extracted is large, we have written a program which will extract selected data/parameters from the ``binary'' database. The contents and the format of the output data is programmable.
This document describes the design of this program. The first part of this document is intended for ``plain'' users of the program while the second half is targeted for more enterprising users who may like to extend this program.