Greetings!
It has been a long time, with many professional activities in between, but I'll soon be back in action covering some or all of a metadata MOOC by Coursera: Metadata: Organizing and Discovering Information. The course begins in July. It seems basic--my first choice was actually a Library Juice Academy metadata course that was dropped.
From this MOOC, I hope to get a better idea of the comparative landscape of metadata systems, and I will be paying specific attention to book and e-book metadata.