Carolyn, are you asking about the "Cotton Theory"? This is reversable. I am working on several now (all my test squares). It is really easy. Her site does not explain it - you need to purchase her book. I went to her class when she was here and love it. No more yards of quilt to heave up and under a needle. :) I included the link to her site here.
I'll have to check that out. Maybe make a visit to the Quilt shop to see what books they have on hand before ordering.