On Mon, 2007-08-06 at 22:37 +0400, Sergei Shtylyov wrote:

    Actually, checking for the presence of all possible perverted
mapping 
props doesn't seem a good idea -- it's simpler to check for the
presence of 
one prop (like "direct-mapped" I was thinking about, or maybe
"simple-map").

Or more simply... if it's not a direct mapping, it doesn't have a ranges
property and can't be walked down by conventional means.

Ben.