In {HEAD ~ alternative}, {TAIL ~ such code} can be interpreted by the CUI 18 as a new microinstruction 
In { HEAD ~ alternative } , { TAIL ~ such code } can be interpreted by the CUI 18 as a new microinstruction
OTH HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH