For example, Anderson (1997) stated more generally: "diagrams are pictorial, yet abstract, representations of information, and maps, line graphs, bar charts, engineering blueprints, and architects' sketches are all examples of diagrams, whereas photographs and video are not".
[2] On the other hand, Lowe (1993) defined diagrams as specifically "abstract graphic portrayals of the subject matter they represent".
The basic shape according to White (1984) can be characterized in terms of "elegance, clarity, ease, pattern, simplicity, and validity".
[4] Elegance is basically determined by whether or not the diagram is "the simplest and most fitting solution to a problem".
Rather a diagram may only have structural similarity to what it represents, an idea often attributed to Charles Sanders Peirce.