How are these neighborhoods typically defined? Are they circumscribed by the commercial streets they abut - and the commecial edges have their own corridor identity? Or do these low-rise mixed use streets typically form the "centers" of the neighborhood unit - i.e. the single family...

I'd love to hear some more detail to what you would describe these lessons/principles of Toronto's unique urbanism. It would satisfy my curiousity about this topic from observation of Toronto via Google Streetview. (Sadly, I have yet to visit your city, but I'm enormously intrigued).