Two independent book sellers (the names of which I have at home...) sent me what I realized were links after accepting my credit card payments. Fortunately, I had downloaded the links to an easy-to-find directory. I doubleclicked on the links and each one took me back to the store and then opened the epub ebook I had bought in Adobe Digital Editions. The books were downloaded in the ADE subdirectory on my C drive (I use Windows XP at home). I renamed each link to indicate which book it linked to, then copied the ebooks themselves out of the ADE subdirectory to a better one. I tested to see they would still open, not being in the "right" place, but they did. In one case, a book was poorly formatted for my Ectaco JBL, so I opened it in Calibre and resaved it as an epub, with Calibre knowing about my JBL's preferences. The ebook then worked correctly.
So mainly I'm writing to note that some booksellers use what I can only call links to allow you to download, maybe as many times as you need to, so save those links
