APP-6A, Military Symbols for Lan Based Systems is the NATO standard for military map marking symbols. APP-6A was promulgated in December 1999. The NATO standardization agreement that covers APP-6A is STANAG 2019 (edition 4), promulgated in December 2000. APP-6A replaced APP-6 (last version, July 1986), which had been promulgated in November 1984. Edition 3 of STANAG 2019 covered APP-6. The US is the current custodian.