XBL Namespace uses the data: scheme

I was just starting to work through the new XBL draft [1] and noticed:

"The namespace of all the XBL elements and XBL global attributes must be: 
data:,520e273a-62ad-4528-bb1e-9652bda76d62 "

I suspect there may be some pre-W3C history to this, but the choice 
doesn't seem consistent with the TAG's emerging consensus that providing 
retrievable representations for namespaces is a good thing [2].  Anyone 
know more about this and/or have an opinion as to whether the TAG should 
comment on this draft?  Thanks.

Noah

[1] http://www.w3.org/TR/2006/WD-xbl-20060619/
[2] http://www.w3.org/2001/tag/doc/nsDocuments/

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Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
1-617-693-4036
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