[Alsa-user] Difference between index=2, and index=-2?

[Nigel H. <cav...@al...>]

When I set index options if cards are ordered incorrectly, I set these as:
index=0
index=1
index=2 , etc

On my Debian installs, including Kubuntu, /etc/modprobe.d/alsa-base, at the 
bottom of the file are options for abnormal drivers that try to grab card0.

All of these drivers are set as index=-2

I looked in the man page for modprobe.conf, but there is no info about the 
values for index options.

What exactly is the difference between index=2, and index=-2?

Just an academic question helping me to be a bit more clued up.

Nigel.