On page 3 of the Pathfinder character folio it has a place at the top for BAB calculation. One box for Racial Hit Dice and three for Class Bonuses. It looks like you're supposed to total theses up for your BAB. Am I missing something here? I thought BAB was taken from the chart for the class you choose.
The catch here is multi-classing. If you have levels in multiple classes, you look up the BAB of each class on their respective charts, and add them all together.
Racial HD are actually treated much like class levels in this respect; the type of creatures (outsider, elemental, humanoid, etc) will tell you which type of chart to use.
If you only have levels in one class it's easy, but it sounds like the folio is trying to be more flexible.