data-* attributes allow XML name characters and they are converted to lower case in HTML (ASCII, AIUI).
BTW, editorial correction for 3.3.3.8 <http://www.whatwg.org/specs/web-apps/current-work/multipage/dom.html#embedd ing-custom-non-visible-data> : should be "its name contains no characters in the range" (because an attribute contains its value). Chris
