Examples

 >IMARK CURR           mark current position
 
 >IMARK ALL            mark positions in current list
 
 >IMARK "SOURCE.LIS"   mark positions in given
                       text file
 
 >IMARK "SOURCE.LIS" SYMBOL=5 COLOUR=3
                       use different symbol and colour
 
 >IMARK SOURCE_LIST    mark positions in given
                       ASTERIX source list file
 
 >IMARK SOURCE_LIST    as aove but number the symbols
 
 >IMARK
  LIST file name> !        input positions as separate
  RA array of RA> ......   arrays of RA and DEC
  DEC array of DEC>.....