?D=A, M=D,?N=D ,?N=A etc

strange addition to urls listing Y!

[GerBot]

Doing a link: search I found many of the inbound links have these variables attached to the end.

e.g. www.domain.com/?N=A

what does this mean?

The variables have nothing to do with the sites listed as far as I can see, so I assume it is a Yahoo thing.