How should touch-action apply to multiple fingers?

In our previous discussions on the semantics of touch-action I had focused
exclusively on single-finger scenarios.  But touch browsers also support
two-finger panning (and of course browsers also have other multi-finger
behavior that is out of scope for this group).  It seems the spec should
really describe how to determine the permitted touch actions when there is
more than one touch point involved.

The behavior I'm getting from IE11 seems quite confusing.  For example, try
two-finger panning at different locations in this test page:
http://jsbin.com/aqEnoPo/2/edit.

Thanks,
   Rick