NUM NUM { $$ = (struct frame_spec_t) {SFACE,$1,$2}; }
| FACING { $$ = (struct frame_spec_t) {$1,0,0}; }
| FACING NUM NUM { $$ = (struct frame_spec_t) {$1,$2,$3}; }
NUM NUM { $$ = (struct frame_spec_t) {SFACE,$1,$2}; }
| FACING { $$ = (struct frame_spec_t) {$1,0,0}; }
| FACING NUM NUM { $$ = (struct frame_spec_t) {$1,$2,$3}; }