I've spent half an hour or so looking at this thread, and my take away is that you're largely just confusing matters even further.

> It's just a file format.

This is clearly incorrect. It does encompass a file format, but it also contains code to manage that file. The existence of sqljet does not change this, it's merely a different database management system that uses the same file format.

You also seem to mostly ignore that the data it's managing is a relational database, not some other form of data. This is why you can't compare it to python's csv module or python-docx, neither of these do anything to restrict you to a relational data model, nor do they provide a system to query them as if they were a relational database. On the other hand, if for some unknown reason you rewrite the storage engine of postgresql to use the either the sqlite file format or csv/docx, I assume you agree it would still be an RDBMS.

Ultimately I think you're just adding to the confusion by saying that a project with 139,000 lines of C code is "just a file format".