Comment 26 for bug 316373

> Interesting, but normative?

Just because the W3C has published something an normative does not mean that it's a good idea or something that Mozilla should implement. As seen from the blog post that dbaron referenced, even the XML Core WG has given up on 1.1. They still try to introduce some of the backwards-incompatible changes as 1.0 5th ed. Backwards-incompatible changes don't make sense for formats that have Draconian error handling.

I expect XML support in Firefox to stay at 1.0 4th ed.

Moving to 5th ed. would just amount to handing vocabulary designers a footgun that takes a spec lawyer to debug. There will always be 4th ed. and earlier parsers around, so it will continue to be a terrible idea to use the characters allowed by 5th ed. but not 4th ed. in an XML vocabulary. (Since such vocabularies will fail spectacularly in 4th ed. parsers.)

If we expect reasonable vocabulary designers not to actually use the new stuff from the 5th ed., supporting the 5th ed. doesn't add any value to Firefox.