Thus CTYPE1 applies to the default WCS, which may be named using WCSNAME. A second WCS could use keywords such as CTYPE1A and WCSNAMEA. Up to 27 (no suffix, A-Z) different sets of WCS keywords may be specified.
In SAOimage, the WCS to be used is specified by adding %WCSNAME to the end of a filename specified on the command line. This is added after the extension of a multi-extension FITS image is specified:
fitsfile,extension_name_or_number%WCS_name_or_letterAn additional nonstandard feature has been added, the keyword WCSDEPx, which is set equal to the name of a WCS which would be found in a WCSNAMEx keyword value or a single character which is assumed to be the suffix for the WCS.