The indicia are made of {HEAD ~ a material} responsive to {TAIL ~ UV emissions} to render the indicia visible 
responsive to
The indicia are made of { HEAD ~ a material } responsive to { TAIL ~ UV emissions } to render the indicia visible
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH