), ▁and ▁was ▁replaced ▁in ▁turn ▁by ▁J oint ▁Sym b ology ▁AP P - 6 ( B ) ▁( APP - 6 B ) ▁in ▁ 2 0 0 8 ▁( ST AN AG ▁ 2 0 1 9 ▁edition ▁ 5 , ▁June ▁ 2 0 0 8 ) ▁and ▁NAT O ▁J oint ▁Military ▁Sym b ology ▁AP P - 6 ( C ) ▁( APP - 6 C ) ▁in ▁ 2 0 1 1 ▁( ST AN AG ▁ 2 0 1 9 ▁edition ▁ 6 , ▁May ▁ 2 0 1 1 ). ▁ ▁The ▁U . S . ▁is ▁the ▁current ▁cust od ian ▁of ▁AP P - 6 A , ▁which ▁is ▁equivalent ▁to ▁M IL - ST D - 2 5 2 5 A . ▁ ▁Symbol ▁sets ▁The ▁AP P - 6 A ▁standard ▁provides ▁common ▁oper ational ▁sym b ology ▁along ▁with ▁details ▁on ▁their ▁display ▁and ▁plot ting ▁to ▁ensure ▁the ▁compatibility , ▁and ▁to ▁the ▁greatest ▁extent ▁possible , ▁the ▁inter oper ability ▁of ▁NAT O ▁land ▁component ▁command , ▁control , ▁communic ations , ▁computer , ▁and ▁intelligence ▁( C 4 I ) ▁systems , ▁development , ▁operations , ▁and ▁training . ▁AP P - 6 A ▁addresses ▁the ▁efficient ▁transmission ▁of ▁sym b ology ▁information ▁through ▁the ▁use ▁of ▁a ▁standard ▁method ology ▁for ▁symbol ▁hierarchy , ▁information ▁tax onomy , ▁and ▁symbol ▁ident ifiers . ▁ ▁AP P - 6 A ▁recogn ises ▁five ▁broad ▁sets ▁of