non-paper
n.— «The SPD sources also confirmed that Soviet Ambassador Semyonov did deliver a “nonpaper” (diplomatic jargon for an unofficial message) in early February that hinted at a message of mediation.» —“Willy Brandt: go-between in US-Soviet dispute?” by Joseph Joffe in Hamburg Christian Science Monitor Feb. 28, 1980. (source: Double-Tongued Dictionary)