John, I don't know whether ALL panelboards use the "4040" nomenclature--as far as I know, there's no provision in the code that requires that. Rather, it's common enough that you can pretty much figure out what the panel is from the number.

There should be a specific mention on the instructions about what is allowed, and what isn't. It may be in the directory part (where "blender" is written in). The diagram in the middle shows only one pole in each position; if a tandem is allowed, the diagram normally shows two poles. I'm thinking that there's some sort of note printed just above the directory that doesn't show in the pictures.