Was bedeutet eigentlich diese Zahl "604",
die manchmal im Zusammenhang mit Goa-Trance erwähnt wird?

Die Inspiration dazu kam von Braden L. Albert, der am 30.10.1996 folgendes Posting über die internationale Trance-Mailingliste "goa@party.net" schickte:
Hey Everyone,

I had a very weird thing happen to me while at a party in Cleveland on
Saturday night.  I was in the main room of this rave at the time.  It must
have been about 4:00 A.M. or so.  I had been dancing to this great
hypnotic trance for a couple hours.  It winded its way from acid to
psychedelic to tribal and back to psychedelic trance like the thumping,
swirling swing of a grandfather clock on LSD.  Anyway, after working up a
righteous sweat, I took a breather on a bench.  The venue was a converted
roller skating rink, so there were plenty of benches on which to sit. 

As I was grooving in my repose to the still rising tide of scintillating
tunes, I looked at this object in front of my and my mouth dropped.  It
was this huge mail bag that had the letter "604" inked on the canvas.  But
the inking was done in such a way that the "6" looked just like a "G" and
the "4" looked like an "A".  So "604" was actually "GOA" in disguise. 
Considering the music and where my head was at the time, it was quite a
moment.  Talk about signs, huh? 

Braden Albert

Die Leute auf der Mailingliste nahmen diese Assoziation begeistert auf und verwendeten immer häufiger die Zahl "604" stellvertretend für "Goa-Trance". Sogar die Mailingliste an sich konnte dann unter "604@party.net" erreicht werden.