Right now, section 5.11 makes references to the work of the Sync Media for Publications CG, and acknowledges that work has not yet been stabilized. The references include specific details such as mime type, file extension, and spec name.

I would like to propose that we avoid referencing specifics and instead use this replacement text for Section 5.11:

"
5.11 Accessibility

This section is non-normative.

The history of the audiobook is rooted in the world of accessibility. To make publications fully accessible, content creators should refer to the Synchronized Multimedia for Publications Community Group regarding creating synchronized accessible content and incorporating it into an Audiobook.

Alternatively, a content creator can provide the text equivalent as HTML [html] resources in the resources.
"

Furthermore, I would delete the Editor's Note as well as Example 13 and leave Example 14.