The patent is US 6,684,513 and they are currently asserting claims 1,8, 15-17, 19-20, 23, 28-29, 31, and 34-37.<p><a href="http:&#x2F;&#x2F;www.google.com&#x2F;patents&#x2F;US6684513" rel="nofollow">http:&#x2F;&#x2F;www.google.com&#x2F;patents&#x2F;US6684513</a>