Whenever I tag a single, I put the single name as the album title. For example, Korn released the song "Never Never" as a single before their album. I it tagged with the following specs:
Album: Never Never - Single
Song Title: Never Never
Song Number: 1
Song Number of: 1
Disc Number: 1
Disc Number of: 1
That way, whenever I browse through my library, I can clearly see singles from their perspective LP/EP albums. That's what works for me though and it's your library, feel free to tag things how you see fit.
I ws hoping I'd not have to shoe-horn the word "Single" into song name / album / etc tags. Are there not any tags that could be used separately? I've looked down the list of tags iTunes provides, and the only thing I can see that might be usable is "Grouping" but I can't figure out what that's actually for (despite Googling).
Grouping wouldn't help you. What you need is a tag entry, easily seen in iTunes, so you can differentiate between the songs that are singles and the songs on the full albums. The only entries that will do that are modifications to the song title or album title.
Grouping is a tag option that is used for classical music, it is used to denote movements in classical works. Classical pieces often have different movements, are performed by different orchestras across many generations, and even different composers. The grouping field is used to make things easier when managing classical works.
The song/album title tags are just that, the song title and album title.
I read things to that effect, but as I seem to be able to type "CD single" into the field, I don't understand how it's different. Is there something hierarchical about the tag, or something else buried in it's code?