This is a Foam Optimized file. When unfolders take a standard Pepakura file and alter it to work best for foam, they will remove many of the smaller pieces that are not needed in a foam build, because the actual thickness of the foam itself will account for that part, whereas when making it out of card stock you will have to fold a piece and glue it there to account of the thickness of the edge.
Here is write up on the differences between unfolds for Foam and unfolds for Paper.
[URL unfurl="true"]https://www.405th.com/forums/threads/foam-vs-pepakura-unfolds-a-guide-to-the-difference.52685/[/URL]