That would be cool, if true. I would like to see what the underlying query looks like, and whether it is efficient.

Yes, these are essentially links to the corresponding rows in the child table. Airtable solves this problem via the "linkedRecordsField", though I'm not sure it's actually "solved", as the interface around them is a bit clunky and having more than a few is pointless as they get truncated and you can't see them regardless.

I've spent quite a bit of time plumbing Airtable's APIs, and am currently developing an app around Airtable to address some of these issues (zemanir.com) in case anyone is interested.

Yep, it's a one-to-many autogenerated backlink, helpful for seeing every e.g. purchase for a user.

The lack of backlinks is one of the big frustrations I've had in other DB apps, since "this thing has many of these" is such a common pattern.