PHP-using HTTP Guru ?

I asked a question about this last week on php-general, but didn't get a response, and was hoping that someone who knows the PHP engine at a deeper level could help me: I am new to the concepts of HTTP, and how user agents communicate with servers via this protocol. I am wondering if all user-agents (such as Perl scripts/spiders, not necessarily just browsers) observe the PHP function 'header("Location: ")' function. I did some reading about HTTP this weekend, and learned that when PHP calls the 'header()' function, it's essentially giving the user agent instructions as to where to go next. In other words, it is not that the web server is actually refusing to serve the page to the user agent, but rather that the user agent is told to stop reading the page that is served and start reading something else. Is this correct? I am trying to keep unwanteds from accessing parts of my site using this idea, but if someone could code their way around this with Perl or something, I don't want to use it. Thank you, Erik ---- Erik Price Web Developer Temp Media Lab, H.H. Brown pricee@hhbrown.com