Actually it may be better to just remove the current sort order field, and have this catalogue option instead.

Right now there are no other category/entry-like content types that have manual ordering, just some resource types where it makes special sense, and Comcode pages.

There are issues for adding a lot more order fields, but I feel it's kind of bloaty, and I would rather have the system consistent until we feel the need to ramp the complexity up.

I've implemented what I said in my comment.

I'm reorganising issues so the concept of order-overrides is handled from one shared issue.