Question

I found the following code in php.ini. what does that mean?

And “PHP registers” — what is that?

; This directive describes the order in which PHP registers GET, POST, Cookie,
; Environment and Built-in variables (G, P, C, E & S respectively, often
; referred to as EGPCS or GPC).  Registration is done from left to right, newer
; values override older values.
variables_order = "EGPCS"

Answer 1

The manual about the directive might help you a bit more : variables_order (quoting) :

Sets the order of the EGPCS
(Environment, Get, Post, Cookie, and
Server) variable parsing. For example,
if variables_order is set to “SP” then
PHP will create the superglobals
$_SERVER and $_POST, but not create
$_ENV, $_GET, and $_COOKIE. Setting to
“” means no superglobals will be set.

Also note (quoting again) :

The content and order of $_REQUEST is
also affected by this directive.

I suppose this option was more important a while ago, when register_globals was still something used, as the same page states (quoting) :

If the deprecated register_globals
directive is on (removed as of PHP
6.0.0), then variables_order also configures the order the ENV, GET,
POST, COOKIE and SERVER variables are
populated in global scope. So for
example if variables_order is set to
“EGPCS”, register_globals is enabled,
and both $_GET['action'] and
$_POST['action'] are set, then $action
will contain the value of
$_POST['action'] as P comes after G in
our example directive value.

I don’t see what I could add ; did this help ?

Or is this something in this that causes you a problem ?