What do you call a system of what visual items mean? Visual items include symbols but also line thickness, color, etc. It could be used for either production or consumption of a designed piece.
For example, you are designing a book and you want a consistent use of typefaces and lines throughout the book. A certain font always means an explanation, another means citation; a certain line always means movement, another means causation. This is standard practice but I can't think of the word.
The word could refer to a physical rulebook of sorts, or just to the visual system even if its never written out anywhere.
"I developed a ____ for the website so that all the designers would make a consistent product and so that readers would easily understand what everything means."
- Visual style guide works a) I believe a better word exists that I am forgetting and b) it seems to refer more to a rule book than to a system.
- Visual system is too vague.
- Visual nomenclature is perhaps the closest by way of analogy. Is there anything that wouldn't require visual in front? Also, nomenclature might not make sufficient reference to an internal logic.