Generally, {TAIL ~ program modules} include routines, programs, objects, components, and {HEAD ~ data structures}, etc. that perform particular tasks or implement particular abstract data types 
Generally , { TAIL ~ program modules } include routines , programs , objects , components , and { HEAD ~ data structures } , etc . that perform particular tasks or implement particular abstract data types
OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH