Pepakura Blue and red lines in pepakura files.

[2007mustang]

Hello to this wonderful and informative group. My question is in my question is what does the blue and red line mean in the pepakura file. I have attached a pepakura file. Does the bus mean undercut or outer cut ? Or outer cut ? Again thanks for anyone that can let me know..and keep on building..

 

[Cadet]

In that image, the blue means there is a fold there and that part is connected to another part. The Red line is an edge that is the end of the piece and is not connected to anything else.