The string is case insensitive. For details of the interface required for each, see the sections below.
Once a function has been provided, a null pointer can be supplied in a subsequent call to astGrfSet to reset the function to the corresponding function in the graphics interface selected at link-time.
int Attr( int attr, double value, double *old_value, int prim )
int Flush()
int Line( int n, const float *x, const float *y )
int Mark( int n, const float *x, const float *y, int type )
int Text( const char *text, float x, float y, const char *just, float upx, float upy )
int TxExt( const char *text, float x, float y, const char *just, float upx, float upy, float *xb, float *yb )
AST A Library for Handling World Coordinate Systems in Astronomy