SAOtng supports FITS files internally, so that a standard FITS image file can be sent directly to SAOtng for display using XPA: xpaset SAOtng Also, when a new file name is sent to SAOtng, the program checks the first 2880 bytes of the file to see if it is a FITS file and if so, processes it accordingly. Support for other image file formats (or any other image format) is added to SAOtng by writing two external file access programs: . ... The command-line of the image section program . ...