I've received an ePub with the following structure:
Abstract Container: META-INF/ container.xml varience.txt OEBPS/ content.opf Great Expectations.opf cover.html chapters/ chapter01.html chapter02.html … other OPS files for the remaining chapters …
There are two opf files contained within it, but only content.opf is referenced by the abstract container's container.xml
I think this valid as I don't get any errors thrown by epubcheck, but I'm having trouble understanding why an ePub would be structured this way. I'm also a little confused by the Open Packaging Format (OPF) 2.0.1 spec as it says under the package conformance section: "it may consist of one or more XML files, but only one may use the file extension .opf."
So I guess my questions are:
- Is it valid to have more than one .opf file? In what circumstances would this be useful?
- Is it valid to list an .opf file that isn't referenced in the container.xml?
- Is it valid to list multiple .opf files if they are referenced in container.xml? How would this be represented in container.xml? How would an ePub reader decide which to use?