The
AST_GRFPUSH and AST_GRFPOP functions are intended for situations where it is
necessary to make temporary changes to the graphics functions used by the
Plot. The current
functions should first be saved by calling AST_GRFPUSH. New functions should then be
registered using
AST_GRFSET. The required graphics should then be produced. Finally,
AST_GRFPOP should be called to restore the original graphics functions.