(green)-“valley”: Indicates a valley fold.

(orange)-“mountain”: Indicates a mountain fold.

(grey)-“crease”: Indicates a crease on the paper. These will be represented only where necessary.

(black)-“edge”: Indicates a paper edge.

(dotted black)-“X-ray” Indicates a paper edge that is hidden by the top layer(s). This is sometimes referred to as ‘X-ray vision’.

(dotted green)-“hidden-valley”: Indicates a valley fold on a layer below the top layer which is the one visible in the diagram.

(dotted orange)- “hidden-mountain”: Indicates a mountain fold on a layer below the top layer which is the one visible in the diagram.

(blue)- “unfold-line”: These lines will be on paper edges already folded. The line indicates that the fold must be undone. Let me call this the ‘unfold line’.

(pink)-“reverse”: Occurring only on paper edges, this indicates that the fold should be reversed. That is, a valley should become a mountain fold or vice versa.