Contrary to what most people think, Knoppix is not Debian and it doesn't behave as Debian. The simple reason for this, is that it is an amalgamation or debian repositories which include woody, sarge, sid, experimental, marillat, and iirc, katame. Consequently, the dependencies are all varied, knoppix is a hell of a distro to use as a live-cd if you leave home, or to install to the hd AS IS, that's why there is a new version every 3 months, or to troubleshoot other os.
Read this article, you will find a reference to fstab:
Knoppix - Instant Gratification