The command HEADER was also modified to get the header information from user variables rather than the image header. When an image is loaded, the header items CRVALX/Y, CRPIXX/Y, and CDELTX/Y are read from the header (if possible) and are then stored as user variables of the same name. For BASIC images (or images with no header information), the user may use the command SET to assign values to these variables and then call HEADER to properly set up the transfer function and the World limits.