When OI tags are applied to ebooks on the SD card, where are they located? Internal memory or the SD card? If I were to take the card out and place it into another reader with the same version of OI, would the tags show up there? Or if I opened the same ebook (but on a different card) on the original reader whould they show up there?

In other words, are the tags some how attached to the ebook itself whereever it resides or are they attached to the reader and linked in some manner to the ebook? Or is there some other possibility that I haven't thought of?

Internal memory right now.

Internal memory right now.

So a reboot loses all tags (and probably bookmarks too as well as the clock setting)??

no, it does not.