Failing epub validation

[vvatikiotis]

Validation of sicp.epub fails with the message

ACC-009 (WARNING) Message: MathML should either have an 'alttext' attribute or 'annotation-xml' child element.

Tested on https://www.epubconversion.com.

Also uploading and conversion of the epub file to Google Books fails due to unspecified error. It could very well be this error.

[sarabander]

Confirmed with http://validator.idpf.org/. Not sure it should be fatal, because all the messages are warnings.
Will investigate how easy it would be to generate alttext for the mathml elements.

I'm afraid pleasing the Google Books converter will take a lot more than annotations. Seems to me they don't support the full spec of epub3.