return value for response handler

[John ORourke]

Hi folks,

I had a bug with an interesting side effect which I want to understand.
I wanted to redirect the user's browser, and in my response handler I 
was setting $r->status(302) but returning Apache2::Const::OK instead of 
the correct Apache2::Const::DONE.

This caused Apache to perform an internal redirect.  Can someone explain 
what was happening in terms of handlers and subrequests or point me to 
the right doc page?

thanks
John