[TechniSol]

Well, the info is contained in the database on the device at least. The collections are synced to the servers irregardless of whether they are populated with sideloaded titles. I'll admit I can't speak to how much data regarding collections is synced, but all they need to do is transfer a page number and some sort of identifier between systems, there is no requirement that it be a book title or any other information. A hashing algorithm of some sort or some other unique identifier would be fine. I'm just asking for them to sync a page number...

If you switch devices between reads, and realize remembering page numbers may not be sufficient due to varying font and screen sizes you'll understand why I'm asking. OTOH, I wonder if those very differences between devices complicate matters, but they do it for their kepub titles.

Normally, it wouldn't be a problem, I'm the guy who closes a book and remembers the page number until opening it again, but depending on how many things I'm reading it gets confusing as multiples pile up.