 size(rframe); char = class(rframe)

               Case and leading or trailing blanks bracketing a non-blank
               frame name are not significant in the string 'rframe'.

      abcorr   the string indicating the aberration corrections
               to apply when computing the 'raydir' direction.

               [1,c3] = size(abcorr); char = class(abcorr)

               The supported aberration correction options are

                  'NONE'          No correction.
                  'S'        