For this case a logic level of a first one of the mode select interface pins specifies {HEAD ~ a circuit block} for coupling to {TAIL ~ the interface pins}, and a logic level of a second one of the mode select interface pins specifies a mode of operation of a specified circuit block 
for coupling to
For this case a logic level of a first one of the mode select interface pins specifies { HEAD ~ a circuit block } for coupling to { TAIL ~ the interface pins } , and a logic level of a second one of the mode select interface pins specifies a mode of operation of a specified circuit block
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH