[Tagging] How to tag pipestems (shared driveways)

[Josh Doe]

How do we differentiate between driveways and pipestems? Pipestems are
common in planned residential developments (at least in the US), where
a number of houses are located off a pipestem, each with their own
driveways. Maintenance of the pipestem is the responsibility of all
the homeowners off that particular pipestem. Pipestems aren't named
roads, so highway=residential doesn't make since, but I'm not sure if
I should use service=driveway both for the pipestems and for the
individual driveways. I suppose I could use operator=*, but since it's
just a collection of homeowners that typically don't have a name, I'm
not sure what to put here.

I don't want to invent a new tag if I don't have to, but I'm not sure
how to use existing tags to make this distinction.

Perhaps I could use highway=service, service=driveway, and
driveway=pipestem? Suggestions are welcome!

Thanks,
-Josh

[1]: http://wiki.openstreetmap.org/wiki/Talk:Tag:service%3Ddriveway#Pipestems