Audit this project for adherence to the HTML Accessibility API Mappings 1.0

The W3C Working Draft of the HTML Accessibility API Mappings 1.0 is far enough along to use in an audit of this project's HTML to AX concept mapping. 

In this Issue, we'll conduct an audit to determine what changes, if any, need to be made to match this spec: https://www.w3.org/TR/html-aam-1.0/