Dungeon World- monster damage notation

My scan of the monster section didn't turn this up...but why do some monsters have the letter b (or w) before their damage expression?

It's built from generating the monsters, but what it means is... b[2d6] means roll 2 six-sided and keep the better. w[2d6] means roll 2d6 and keep the lowest, basically.

I forget which steps of monster creation, which options that give these, but this is basically what it means.

- Alex

This was posted on RPG.net 07-07-13