W3C:

2008-05-08: The XHTML2 Working Group has published the Last Call Working Draft of CURIE Syntax 1.0, which outlines a syntax for expressing URIs in a generic, abbreviated syntax ("Compact URI"). The specification targets language designers who need a mechanism to permit the use of extensible value collections. Any language designer considering the use of QNames in attribute values should consider instead using CURIEs, since CURIEs are designed for this purpose, while QNames are not. Comments are welcome through 10 June. Learn more about the HTML Activity. (Permalink)