Sound programming: Tone production in Python?

[Peter Hansen]

Andrew McGregor wrote:
> 
> sndarray just gives you a way to access raw sample data.  If you want to
> make tones, calculate a sine wave with the right period, amplitude and
> zero-offset (which will depend on the output format and sample rate), and
> use sndarray to play it.

Just a stray question: what do you mean by zero-offset in this context?
I've written signal generators that can output arbitrary periodic waveforms
including sinewaves in this manner, but I don't recall ever having to 
worry about anything I would have called the "zero offset".

-Peter