{HEAD ~ This output} can be utilized to set {TAIL ~ the variable node processor} to use different update functions 
{ HEAD ~ This output } can be utilized to set { TAIL ~ the variable node processor } to use different update functions
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH