Agreement on HTML Ruby Markup

The W3C can specify extended HTML Ruby markup (based on PR#6478) under the REC track. This will be a derived document with some textual copying from WHATWG HTML and W3C HTML Ruby Markup Extensions, but the W3C and WHATWG mutually agree that publishing it is within the bounds of our MoU.

W3C editors can offer pull requests to keep the HTML spec in sync, both technically and editorially, for the subset of features defined in both specs, so that readers of both specs can benefit from any improvements. Once the criteria for addition to WHATWG Living Standards are met, W3C editors can also offer pull requests to fully integrate the extended ruby markup definitions into WHATWG HTML. WHATWG HTML editors will review these contributions in good faith, and merge those they deem acceptable under the WHATWG working mode.

The SOTD section of the W3C Ruby Extension spec will link to this agreement.