/usr/local question

[Jan Stary]

> > I just find it quite extreme to expect the user to not have
> > /usr/local around. The reason macports uses /opt/local (if I am
> > not wrong) is that macports realizes that people *do* have
> > /usr/local around.
> 
> I, personally, have had /usr/local around for forever. The issue is that if you don't know it can interfere (and can't diagnose and fix any instances when it does), it's very difficult to help you if/when you have problems.
> 
> So, the 'safe' advice we give people is "don't do that"

OK, I can understand that. Did I really miss this bit
in the documentation? Can someone point me please?
I believe it should be clearly stated in the Guide.