Calculating white mortal wound (and PTGS)

Just something I’m wondering out of curiosity - is there a special way to calculate mortal wound when both forte and power are white, and if yes, what is the formula?

Since gray power and forte has a special calculation I thought it seemed reasonable to assume there would be one for white as well.

Off the top of my head, Supie and Light are both double Forte, and then you count back the others from mortal.

so for W6 Power and Forte:

Su: B12 Li: G8 Mi: W8 Se: W10 Tr: W11 MW: W12

Alright, thanks! Was this in the monster burner or some other OoP book?

Yes, it was in the Monster Burner.