In one embodiment, coatings of initially colorless color formers and color developers are coated on {HEAD ~ selected areas} of {TAIL ~ a substrate surface} 
In one embodiment , coatings of initially colorless color formers and color developers are coated on { HEAD ~ selected areas } of { TAIL ~ a substrate surface }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL