filter waveform question

[Paul Eccles]

>The order of a low pass filter is equal to the number of parameters
>which can be varied independently. A first order filter has only one
>parameter, the cutoff frequency (Juergen mentioned a 6dB/oct filter with
>resonance recently, this cannot be a first order filter then). A second
>order filter has two parameters, these can be fc and Q.

If I have two second order filters and whack them in series, what are the
two new parameters I've just scored?

Also, there are second order filters that give you independent control of
more than two parameters. The Tow Thomas biquad is a good example - cut-off,
Q and gain.

Paul.