parsing order?

[tbbd]

I looked thru the php.net site and was unable to find any reference for this, but is there someplace that has like a listing of what gets processed in what order when php reads the files

like for example, when you a call a variable at the "top" of the page but it is not defined until the "bottom" of the page, that doesn't work, yet when you make a function that calls another function that is "located under it", it works, so maybe all the functions are read into memory or something before any processing even happens..I have no idea
and sometimes I have trouble with using header() and the cookies, and the sessions, becuase I always gets header already sent msg or something similiar

so what I'm looking for is something that just says what happens
I know this is not right, just something like this
session_register
session_start
cookies sent
header sent
all functions read
code processed from top of page to bottom

[Installer]

It's not the order of parsing, it's the order of execution that matters. Code in the global scope is executed in top-to-bottom order. If a statement that causes HTML output is executed (echo, print, etc) or text outside the PHP tags is encountered (which is by default HTML), then, by protocol, HTTP headers must first be sent. So if they haven't already been sent, and buffering isn't turned on, then before sending the HTML the server will send the headers. Once this has happened they can't be sent again and an attempt to do something that involves the headers (set cookies, send more headers, start a session, etc.) will fail.