A software module may comprise a single instruction, or many instructions, and may be distributed over {HEAD ~ several different code segments}, among different programs and across {TAIL ~ multiple storage media} 
across
A software module may comprise a single instruction , or many instructions , and may be distributed over { HEAD ~ several different code segments } , among different programs and across { TAIL ~ multiple storage media }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL