COM and "by reference"

[Uffe Kousgaard]

This calls a method on a COM object:
$returnvalue = $commodule->method($var1,$ var2)

If var2 returns a value too (a so-called "by reference" variable), is it
then needed to use a special syntax? Declare var2 in advance?

I'm a beginner in PHP, but needs to update a few parts of an existing
application.

TIA
Uffe