Origami diagrams are a means of communication, using symbols rather than words. The symbol set used these days is largely the same, based on the set developed by Yoshizawa and Randlett in the 50’s. Like any language, variations (dialects?) have developed and new symbols have entered the set from time to time.
Since I am producing diagrams almost every day, I am constantly striving to find better ways of illustrating a given step. My style has developed over the years and one change I made a few years ago was to replace the old double line “crease and unfold” with a single line using hollow and solid arrowheads. This didn’t offer more information, but made the drawings cleaner.
More recently, I have begun to use the dotted line, in two ways. Firstly, to show where a flap is folded underneath a layer. Previously, I used a cut-off arrowhead, but this didn’t allow me to specify exactly where a point would finish up. My new technique is;
1) draw the line in its entirety
2) cut the line where it meets an edge, then convert the line to dots
3) add an arrow-head at the end
Secondly, I have used dots to help make folds that have no obvious location points. Traditionally, the reader is supposed to look ahead at the next drawing to work out where to fold to. For example, here I am making a precrease for a reverse fold. The sequence is;
1) Draw dotted lines to match the edges that will be reversed (shown here slightly offset so you can see them).
2) Use the reflect tool, select the lower point as the point of reflection, then flip the shape over.
3) Add the arrows (using my current fold and return style).
The result is an accurate illustration of where the paper will go, allowing the reader to make use of any reference points they can. Another bonus is that when the reverse has been made, you can quickly convert the dotted line into the reversed paper without having to redraw it.