Antedating of "A.A."

[Bethany K. Dumas]

On Thu, 13 Nov 2003, Fred Shapiro wrote:

>A.A. (OED 1943 for organization, 1941 for members)
>
>1940 _Washington Star_ 5 May in _Alcoholics Anonymous 1939-1942_
>Attention was drawn to the movement recently by a dinner that John D.
>Rockefeller, jr. ... gave for 60 A.A.s at the Union Club in New York.
>
>1940 _Richmond Times-Dispatch_ 18 July in _Alcoholics Anonymous 1939-1942_
>This is a common characteristic of any A.A. meeting.

This? What is the "common characteristic"?

Bethany