Permanent Notes
Permanent Notes are a concept in Zettelkasten. David Kadavy has a great description in Digital Zettelkasten:
Permanent notes are explanations of a single idea, annotated with metadata about the subject of the note, other notes that note is related to, and the source of the note.
For me, I use the topic tag, and Topic Notes.
Andy Matuschak calls these ๐ Evergreen Notes which is also a great name for them.