{HEAD ~ Masks} can be used to form {TAIL ~ a pattern} of crosslinked and non crosslinked regions on a surface 
used to form
{ HEAD ~ Masks } can be used to form { TAIL ~ a pattern } of crosslinked and non crosslinked regions on a surface
HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH