When I "entered" fandom, back in the early '90s, fic was mostly in fanzine form still, but migrating to the 'net via MUDs and newsgroups and mailing lists.
Here's the thing though, most fic, regardless of source or fandom, was sorted into one of three categories: Gen, Het, and Slash.
Gen had no romantic pairings, but might focus on a character or two. Those characters would be listed with commas. (Kirk, Spock, McCoy)
Het was, as implied, heteroromantic and/or heterosexual and the pairings were represented by an ampersand. (Spock & Uhura, Kirk & Chapel)
Slash was not het or gen. Pairings were represented by a slash symbol; hence the name. (Kirk/Spock or Kirk/Spock/McCoy)
I lost track of the fandom communities for a bit in the late 00s/early 10s, discovering that LiveJournal had died, but AO3 was born (🎉🎉🎉) during my hiatus.
I was very confused by the change in the common useage of the & and / symbols, though I rather like the new system because it allows for a greater romantic diversity.
I learned, but I know there are older stories who's writers are no longer around who used the older system.
I also still see folks choosing all the tags for their pairings... possibly because it's not well explained anywhere or there are confusing descriptions depending on where you look?
Anyhoo... something to keep in mind. Or maybe I'm misremembering and should just go back to my corner. 😋