hot spot " ▁of ▁the ▁image ▁relative ▁to ▁its ▁upper ▁left ▁corner , ▁e . g ., ▁when ▁used ▁as ▁a ▁mouse ▁cursor ▁or ▁a ▁" p aint ▁br ush ". ▁It ▁is ▁optional . ▁ ▁S PR T : ▁Z - order ▁ ▁The ▁S PR T ▁chunk ▁indicates ▁that ▁an ▁image ▁is ▁intended ▁to ▁be ▁a ▁sprite . ▁It ▁should ▁thus ▁have ▁a ▁mask ▁plane ▁or ▁transparent ▁colour ▁and ▁shouldn ' t ▁be ▁full screen . ▁How ▁this ▁is ▁handled ▁depends ▁on ▁the ▁program ▁using ▁the ▁image . ▁The ▁only ▁data ▁stored ▁here ▁is ▁the ▁sprite ▁order , ▁used ▁by ▁many ▁programs ▁to ▁place ▁the ▁sprite ▁in ▁the ▁for eground ▁( a ▁sprite ▁of ▁order ▁ 1 ▁appears ▁behind ▁one ▁of ▁order ▁ 0 , ▁etc .) ▁ ▁It ▁is ▁optional . ▁ ▁T IN Y : ▁Th umbnail ▁ ▁The ▁T IN Y ▁chunk ▁contains ▁a ▁small ▁preview ▁image ▁for ▁various ▁graphics ▁programs , ▁including ▁Del ux e ▁P aint . ▁It ▁is ▁com pressed ▁and ▁is ▁similar ▁in ▁format ▁to ▁the ▁B OD Y ▁chunk . ▁ ▁Notes ▁for ▁working ▁with ▁IL B M ▁ ▁Color ▁Maps ▁ ▁Sometimes ▁an ▁IL B M ▁file ▁contains ▁only ▁a ▁colour ▁map ▁and ▁no ▁image ▁data . ▁O ften ▁used ▁to ▁store ▁a ▁p alette ▁of ▁colours ▁that ▁can ▁be ▁applied ▁to ▁an ▁image ▁separately . ▁In ▁this ▁case ▁the ▁B OD Y ▁chunk ▁should ▁be ▁empty ▁and ▁the ▁num Pl anes ▁field ▁in ▁the ▁B M HD ▁chunk ▁will ▁be ▁