Can I just go ahead and make my ebook?
It depends: if the files you uploaded are the ones you want; the spine contains the right files in the right order; if you have fallbacks for all your non-compliant media and alt attributes on all your image files, then you can go ahead and make the book. Usually, however, you have to manipulate files as described below in order to shape your publication and make it OEB compliant. If you try to make a book before you have specified alts and fallbacks, your publication won’t be valid.
