BLD: externally defined frames

Christian and I read the new text explaining external frames in BLD 
[http://www.w3.org/2005/rules/wiki/BLD#Terms] and although we each had a 
different understanding of what external frames were, it matched neither, which 
is problematic.

Given the time constraints I think the only choice is to leave that text as is 
but label it at-risk for last call & open an issue.  Then we can discuss it 
further during the summer.  We hope to propose and resolve that quickly - I 
specifically don't want to get dragged into a lengthy discussion of what 
external frames are, just a quick decision to label at risk so we can publish, 
and we'll have the lengthy discussion later.

-Chris

-- 
Dr. Christopher A. Welty                    IBM Watson Research Center
+1.914.784.7055                             19 Skyline Dr.
cawelty@gmail.com                           Hawthorne, NY 10532
http://www.research.ibm.com/people/w/welty