It shows a rectangular fold that has sides that rise up from the centerfold.
Valley Fold
It has a side that slopes down from the centerfold
Mountain Fold
It shows a rectangular sheet of paper folded in half along the long side.
Hamburger Fold
It shows either raw edges or edges resulting from fold.
Thick Lines
A diagram shows how to fold the corner of a sheet of paper over to create a triangle.
Taco Fold
A diagram shows in a rectangular sheet of paper folded in half along the short side.
Hotdog Fold
It shows crease lines which are the result of prior folds
Thin grey lines
It shows that the fold is supposed to be valley fold.
Dash lines
A fold that finds the midpoint on a piece of paper, folded each side to meet that point.
Shutter fold
A line that is hidden behind layers of paper.
Dotted lines
