Knee armor templates

Hey everyone. I've decided to make some attempt at finishing my knee armor this weekend, Lord willing, and the creek don't rise. I'm just confused about the side blocks for the darts. On the last page of WOF's templates, it shows the Knee Dart drilling and shaping templates. I understand that the rectangular box with the holes is the block the darts attach to, but what are the funky curved rectangles beside them?

The shapes with the centering drill marks are the front profile. So does that make the other shapes the back profile? Anyone out there know?

I treated that as the outer face (the last 1/16" piece in the stack). Just folded it over the edge.

--Jonah