Vincent asks, "So how does one go about getting buy-in? Are the interested parties on this mailing list, or do you have contact information for decision makers in the various voting organizations?"
I think you, Khaled, Michael and others have made a very good case for having some way to render multiple combining marks on a base character that doesn't belong to any particular script. A special character for the purpose may be the right way, NBSP may be okay (if people would only implement multiple combining marks with it) or generalizing shaping engines to allow combining marks to be used with arbitrary bases (Khaled's approach) may be better. We need to brainstorm a bunch to figure out how hard things are. I can't promise anything other than to say I'll discuss it with my colleagues at Microsoft and the UTC. Unfortunately I don't see any easy workaround for you while a solution is being pursued. If displaying no base character is adequate, you could use a currently valid base character and change its color to white. Then at least you wouldn't see a base character, unless it's on a darker background. Murray
