When I started building a new index card note box, I followed Scott Schepard’s lead and used the Wikipedia Academic Disciplines as the overarching structure. I’ve come to dislike that system. It’s too dependent on hierarchy, and one I don’t really follow. So, this morning, when trying to install a new note about Libertarianism (topical!), I became frustrated and renumbered everything.
I’m now using a simpler, more Luhmann-like card numbering system. (Some would call it “Folgezettel”, but I’ll stick with “numbering system”).