pdfeb09,
Yes there is a spillover concept in FB as well. It is explained in every VB.
F2A has some strange rules where some approvals are exempt from the numerical limits.
In particular,
NO Mexico F2A approvals count against the 7% limit.
In the August VB for example, it says :
Of the 44,732 FB visas that Mexico received, 34,363 were in F2A.
So for calculation purposes (at least as I understand it) Mexico received (44,732 - 34,363) + 9,347 = 19,716 visas, which is 5.39%.
Glad my efforts are appreciated. I have been waiting a long time to post the figures for FY2011.
Those extra numbers for EB2 came at the expense of EB3 and EB3-ROW in particular. I don't think they would share your view, since they lost numbers left, right and centre for various reasons in FY2011.