mutt threading contains * and ?

[Anthony Campbell <ac@acampbell.org.uk>]

I notice that threads in mutt now often contain * and ?  - e.g.

	-*-?-?->

I assume this is a new feature(?) and must mean something, but I can't
find it documented anywhere. Is it?

Anthony

-- 
Anthony Campbell - running Linux GNU/Debian (Windows-free zone)
For an electronic book (The Assassins of Alamut), skeptical 
essays, and over 150 book reviews, go to: http://www.acampbell.org.uk/

Our planet is a lonely speck in the great enveloping cosmic dark. In our
obscurity, in all this vastness, there is no hint that help will come
from elsewhere to save us from ourselves. [Carl Sagan]