This is the issue tracking repository for Core Accessibility API Mappings (core-aam). You can read the Editor's Draft version of the specification here.
You can also compare against the most recent published version here.
To open a PR, please see the main ARIA repository where the specification lives. This specification is part of the ARIA suite, and uses the same code structure and build tools as other ARIA suites. General information about editing specifications is in the main ARIA repository readme.