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