If you were able to gather and measure a wide array of Griswold pieces-- skillets, lids, pots, grills, toys, etc, and measure the different styles of logos, you'd find quite a bit of variation. The BB info you reference is a broad, simplistic definition of the logos, and more serves to explain references in descriptions elsewhere in the book, which are quite brief in nature. Although very good reference works, the RB and BB are the product of the experiences of the two authors and a handful of consulting individuals at the time of their publication. In the interim, however, a good number more observations have been made by the collecting community-at-large, and those newer findings have not necessarily found their way into revisions of the BB and RB.