what to make external (ISSUE-78)

At the F2F we had a lengthy but ultimately inconclusive discussion on what to 
allow in an external call:

1) ATOM
2) ATOMIC
3) ATOM | FRAME

In a straw poll, one person objected to each choice, and there were 3, 6, and 2 
people resp. who preferred each choice.

While more people prefer choice 2, it would require re-doing last call.  1&3 
would not, as 1 is covered by external frames being at-risk, and 3 is the way 
the spec reads now.

Let's try and come to some sort of closure by email.

-- 
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