Warning light..

Hello,
 
 I no longer have a book for my audi quattro A6 2001. I have a warning light.. a solid circle with parenthesis type marks on both sides. (O) The circle is filled in. Please advise as to what that might indicate.  Thank you! Jana4444

(O) is a brake pad warning light.
apparently you need new pads and maybe rotors.
my source was google and it is my best friend

http://answers.yahoo.com/question/index?qid=20071026213115AAdTDxd&show=7

Either that, or the sensor wires have a corroded/broken connection.
 
Bascially it's a wear sensor for your pads (front only)