If {TAIL ~ the vector length} exceeds {HEAD ~ the threshold map value}, the block 1260 is entered, the vector is retained unaltered, and it is preceded with a 1 bit 
If { TAIL ~ the vector length } exceeds { HEAD ~ the threshold map value } , the block 1260 is entered , the vector is retained unaltered , and it is preceded with a 1 bit
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH