You should try to pick a UTI that represents your Service
accurately. If the UTI you pick does not conform to any category,
then it will wind up in General. But if later Apple adds a new
category, and your Service's UTI conforms to the new category's UTI,
your Service will show up in the new category.
OK, but what if the service has a category but no real UTI? For
example, there's a "Searching" category. What's the UTI for searching?
I've looked at the list of system-declared UTIs and there's nothing
with "search" in its name.
I'd also better file a bug report about the lack of documentation for