[MlMt] Is there any documentation on operator syntax?

[Kee Hinckley]

In particular, the difference between =[x] and =[c]? But anything would 
be helpful!

I'm trying to constructor a selector for messages that aren't from me. 
The ``Personal Inbox`` example uses:

	filter = "#recipient.address = $SENT.from.address";

for messages which *are* to me. Unread messages uses:

	filter = "#flags.flag !=[x] '\\Seen'";

to exclude anything containing a tag.

So I would guess that it should be something like:

	$SENT.from.address !=[x] from.address

except that crashes MailMate, so I guess not! :)