[bcrowell]

Thanks, itimpi and Kovid, for the replies :-)

Originally Posted by kovidgoyal

I don't see why it should require the file extension to be xhtml.

Section 2.1.1 of the spec says, "The XHTML Content Document filename should use the file extension .xhtml." But it's only a "should," not a "must." I doubt that epub 3-compatible readers would care.

Originally Posted by kovidgoyal

The mimetype is set to application/xhtml+xml (that is needed for epub 2)

I see. What Calibre generates for me in the actual files is:

<meta content="http://www.w3.org/1999/xhtml; charset=utf-8" http-equiv="Content-Type"/>

But in the package document each item is stated to be application/xhtml+xml.

Originally Posted by kovidgoyal

Really the only thing that needs to be done is converting xhtml 1.1 to html 5 which should be fairly trivial, except in the case where the document contains namespaces other than svg/mathml.

The spec also requires this:

"The mathml [Publications30] property of the manifest item element indicates that an XHTML Content Document contains embedded MathML."

There is a similar requirement for SVG.

Originally Posted by kovidgoyal

But you still wont have any readers capable of displaying the MathML

Right, but it would be fun to get ahead of the curve and be ready with a epub 3+mathml book when the first mathml-capable readers come out. I assume this will happen fairly soon. The mathml rendering code is all available under permissive licenses, and since math and science textbooks are so lucrative for publishers, I'd assume there would be a huge economic incentive for Apple and B&N to come out with mathml-capable readers. It would allow them to differentiate themselves from Kindle, which is apparently not going to support mathml in the foreseeable future. It's very different from the situation with MS and Internet Explorer, where MS suffers no competitive disadvantage from its failure to support mathml in a standard way.