When you start to download a protected Adobe PDF or ePUB a small file with the extension .acsm is first downloaded. This is used by Adobe Digital Editions to send the activation ID to the delivery server which will use that ID to generate an encrypted PDF or ePUB eBook, which is then downloaded to your PC.
I located the PDF version of the book that Digital Editions downloaded but it would only open with Digital Editions on my MacBook. I transferred the book to my Kindle and I was told the book has embedded features my Kindle doesn’t support. So much for that idea.
It is handy to have the ebook on my MacBook but that is really not where I want to read ebooks. I want to read it on my Kindle. kalahari.net also sells books in epub format which is also the preferred book format for Apple’s iBookStore (not available in SA so you need to have an US iTunes Store account) and probably also for Google’s anticipated ebook store when that launches sometime this year. Amazon doesn’t support epub yet and this also presents a challenge. We are starting to see the effects of a fragmented ebook format system where not all ereaders can support the main ebook formats. That may suit the providers and publishers but it doesn’t suit users at all. Ideally my ereader of choice should support the books I want to read, DRM’d or not.