BElder: Thanks for the correction. I should have noticed that the small dimension of the outflung was the same as the upright frame members, thus 2 by. Well, that was going to be my next guess.
When in doubt, use the David Niven method: called upon your mistake, say you meant something else. When the something else proves to be wrong, tell them "I didn't say it!" Kinda tough when it's posted in black and white, though.