" ▁in ▁the ▁lower ▁left ▁corner ▁indicated ▁the ▁first ▁row , ▁a ▁" B " ▁the ▁second ▁one , ▁the ▁" C " ▁the ▁third ▁one , ▁etc . ▁The ▁columns ▁were ▁indicated ▁according ▁to ▁the ▁same ▁scheme ▁in ▁the ▁lower ▁right ▁corner . ▁Thus ▁the ▁top ▁left ▁stamp ▁had ▁the ▁letter ▁combination ▁" A " ▁- ▁" A ", ▁the ▁bottom ▁right ▁stamp ▁had ▁" T " ▁- ▁" L ". ▁As ▁a ▁result , ▁ 2 4 0 ▁different ▁st amps ▁were ▁made ▁for ▁each ▁plate ▁used . ▁This ▁was ▁intended ▁to ▁prevent ▁forg ery . ▁ ▁She et ▁edge ▁The ▁term ▁" sheet ▁edge " ▁refers ▁to ▁the ▁empty ▁fields ▁connected ▁to ▁the ▁st amps ▁and ▁arranged ▁around ▁the ▁sheet . ▁These ▁fields ▁are ▁often ▁un print ed . ▁However , ▁in ▁many ▁cases , ▁quite ▁a ▁bit ▁of ▁interesting ▁information ▁can ▁be ▁found ▁on ▁them , ▁e . g . ▁printing ▁dates ▁or ▁the ▁like . ▁The ▁most ▁important ▁ins cri ptions ▁printed ▁on ▁the ▁edges ▁of ▁the ▁sheet ▁are : ▁number ▁of ▁the ▁edition ▁sheet ▁ins cription ▁( ad vert is ements , ▁information ▁about ▁the ▁stamp ▁issue , ▁etc .) ▁printing ▁dates ▁internal ▁numbers ▁registration ▁marks ▁plate ▁numbers ▁band ing ▁ ▁counter ▁of ▁the ▁row ▁value ▁ ▁Special ities ▁There ▁are ▁several ▁special ities ▁of ▁the ▁printing ▁of ▁sheets . ▁The ▁most ▁important ▁are : ▁St . ▁Andrew ' s ▁cross es ▁se - ten ants ▁ ▁See ▁also ▁M ini ature ▁sheet ▁Post age ▁stamp ▁book