Symbolism as Structure Markers
Inspired by what I call the "galaxy symbol" in the titles—of—some—of—Andy Matuschak's—notes which he uses to indicate an "outline note" (relevant tweet) I have taken to creating my own symbolry to define conceptual structures and page-types in my own note-taking system.
Mental model: Δ
The triangle indicates structure, these pages are mental models and frameworks I have come up with for structuring thought. A framework for structuring thought is also a framework for asking good questions.
Solar system: ʘ
Inspired by the Andy's galaxy symbol, I use this "solar system" symbol with similar intent. These are pages which serve as outlines or collections of various notes surrounding a given topic.
While I haven't yet used this symbol myself, pages marked with the galaxy symbol will serve as even broader big-picture notes which may contain a collection of solar system notes.