Field manual 21-30 is intended to supply the information required by the map reader.

History

• 1968-09-16: Change No. 2
• 1965-06-30: Military Symbols [pdf]
• 1961-05-05:
• xxxx
• 1945-02-28: Change No. 3
• 1945-02-15: Change No. 2
• 1944-04-21: Change No. 1
• 1943-10-15: [pdf]
• 1942-07-27: Change No. 2
• 1942-05-09: Change No. 1
• 1941-11-26: This revision [pdf] supersedes Training Circular No. 48, 1941, too.
• 1939-08-01: