a character for an unknown character

[Michael Everson]

I still believe that we need INVISIBLE LETTER http://unicode.org/review/pr-41-invisible.pdf

I think that for the display of combining characters without a base character that the recommended NBSP makes no sense. NBSP is supposed to glue the characters on either side of it to itself. It makes sense that the following character, say COMBINING ACUTE ACCENT, would be glued to it. But why should the two of those be glued to whatever precedes?

Michael Everson