The paragraphs I need describe the file formats you believe you'll need for your API: I need something like "file format WT-1: variable length byte string key, variable length byte string data, no relationship between any of them other than a sort order".
Well, your thinking about secondaries and how to do column-store does drive this, I'm thinking? Or, better, how you're going to related columns in separate files.
Anyway, the reason I'm asking for this is because I'm spending time fixing some file formats that I'm pretty sure will not exist, at least in the current form, in the future.