Forgive me if if this has been answered before, I did search the forums but could't find it.

How is the under apron and under apron pleat lenght determined in the XKILT? I'm using the instructions here http://www.geocities.com/alanhsails/X-Kilt_final2.pdf

I have read through the instructions a few times and can't seem to figure out where the numbers are coming from in appendix 1.

Thanks for the help!!