Electric timer with {HEAD ~ program carrier} switchable from a short term to {TAIL ~ a long term program} 
switchable to
Electric timer with { HEAD ~ program carrier } switchable from a short term to { TAIL ~ a long term program }
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL