PHP should have some way of referencing various types of
passed variables to php script.
Example:

<? SetCookie ("variable","value1", time()+3600); ?>
<form action="submit.php?variable=value2" method="post">
<input type="text" name="variable" value="value3">
<input type="submit">
</form>
 
As you see this form creates 3 variables named variable
(Cookie,URL,Form) there could be also CGI client variable.
and when form submited to submit.php, nobody knows which one would be used as $variable

Solution:
PHP should be able to reference all of those variables
as example: $Form.variable, $URL.variable , $Cookie.variable
            $CGI.variable
and if variable used as simple $variable, php should check
all of them in specified order until finds first, and use
it's value.

I see it as must-have for sites which work with big ammount
of variables and using other script engines with PHP.
____________________________
Thank you for Your attention
And Great Product.

Nikolai.