In other words, while the substantially non dissolvable region or layer may be somewhat soluble in water, the dissolvable region or layer will have a substantially greater solubility in water so as to dissolve, leaving {HEAD ~ the non dissolvable region} or layer substantially intact at {TAIL ~ the end} of the useful life of the shaped composition 
In other words , while the substantially non dissolvable region or layer may be somewhat soluble in water , the dissolvable region or layer will have a substantially greater solubility in water so as to dissolve , leaving { HEAD ~ the non dissolvable region } or layer substantially intact at { TAIL ~ the end } of the useful life of the shaped composition
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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH