Dave: "As oposed to "official cubit", that sign may signify simply measurement rule for example?"
Does Iverson or Petrie give any reason or compelling evidence that Aa11 / 12 signifies "measurement rule "? What does the reference Petrie (Medum, 32) refer to - which Petrie book?
According to J.P. Allen, who is today, one of the foremost experts on AE language, Aa11 (Aa12) is the phonogram mAa, and the determinative in TntAt, 'platform' - he makes no mention of a cubit, neither does Gardiner.
The earlier version of the sign (Aa12), for example used in Sneferu's Horus name, is a long narrow rectangle. The later version of the sign with one beveled edge resembles a cubit rod, but it also resembles a platform or plinth, and as Aa11 / 12 is the determinative in 'platform' (TntAt) - that should more or less settle the matter in favor of platform, unless you have compelling evidence in favor of it being a cubit rod.
you wrote: "It also seems significant, to me, that during Sneferu's reign great leaps forward in building technilogy were made, while Sneferu's name had the glyph for cubit on it, in its role as signifying truth."
This is only conjecture at this point, not fact.
CT