I'll attach a patch that corrects qualified name validation. This fixes one bug where we were rejecting "_" prefixes because our old validator had that wrong. Also fixes a couple tests from the DOM XHTML test suite.
Created attachment 4280 [details] add validity checks that match the XML specification
Fixes <rdar://problem/4291810> DOM 5 Exception when attribute name in document.setAttribute begins with underscore
Comment on attachment 4280 [details] add validity checks that match the XML specification r=me
*** Bug 3622 has been marked as a duplicate of this bug. ***
Mass moving XML DOM bugs to the "DOM" Component.