Found in the Oshkosh Daily Northwestern, September 21, 1939 (page 4)–just as World War II was beginning:
McComb, Miss.–AP–The McComb Daily Enterprise gives confused readers a hand up by labeling each war story.
Its four symbols and their meaning
V — Verified.
OP — Official propaganda.
A — Seems authentic.
R — Rumor.
Good system. Everyone should adopt it for all political news.