These dyes are suitable for use in thermographic imaging systems wherein {HEAD ~ the leuco dye} is in {TAIL ~ a composition} containing a nitrate salt 
is in
These dyes are suitable for use in thermographic imaging systems wherein { HEAD ~ the leuco dye } is in { TAIL ~ a composition } containing a nitrate salt
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH