Is a graphic that shows mainly code a listing or a figure? I am using the following (graphical) element in a document to introduce the concept of a linear revision control history:



Once printed, it is, by definition, a listing ("a printed list of lines of computer code") . Actually, three listings. But clearly it has visual elements beyond a typical listing. In fact, the source code doesn't even serve the purpose of the graphic.

So: is it a listing or a figure?
Should the caption say "Listing x.y" or "Figure x.y"?
It' s a figure. Without the graphical elements, it is not comprehensible any more. A listing could be formated in other ways without changing the meaning, but changing the graphical elements would change the meaning.