I was watching an episode of Still Open All Hours earlier and it got me thinking about canon. Specifically is it just a sci-fi thing or can it be extended to other kinds of programming?
<t>An Autie but not a naughty.</t>
The term comes from religion I think (which Biblical texts are canonical and so on) so isn't necessary limited to sci fi but it probably turns up more there because Star Wars/Doctor Who have more spin off media which is readily discarded by later Film/TV installments.
You could probably apply it to anything that disregards a previous installment - eg did the revival of Will and Grace effectively render the previous ending non-canon?