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I think I've found some good evidence for my position on trapping of metal fonts in general, and Tetterode's Pascal* in particular.
It's from "Dutch typefounders' specimens" (Lane and Lommen). The photo is about 11 years prior to the production of Pascal, but I suspect not much had changed in the meantime.
I think one of those young'uns in the first row simply messed up that "b".