I don't really know anymore. When you can buy your bondage pants and Doc Martens at the mall, and have a mohawk and sleeves of tattoos and work at Wal-Mart, I'm lost. Punk, like just about everything else, has been bred out by other scenes and pretty much void of any real definition as far as a textbook answer to the question of "what is punk?" Don't get me wrong, there are still great punk bands out there, but where the line is drawn is anybodys guess. I would equate it to Heavy Metal/Hard Rock/Speed Metal etc, of which there are both attitude and musical definitions, but have homoginized in to something less cut and dry.
DIY also has a whole new meaning today, with all of the networking, advertising, and selling your music. One guy who could really give you whole picture is Ian Mackay of Minor Threat/Fugazi fame. When there was no MySpace, no internet radio, and regular radio and record labels wouldn't touch you with a ten foot pole, you had no choice. Or, like so many great old punk bands, you just broke up.
So again, on so many levels, I wouldn't know how to answer that question, or even if it's relevant anymore. Kinda puts a safety pin through my heart writing this.
