I inherited a script that uses JavaScript to open a popup window (a php file) hosted on another website. At the same time, it's supposed to pass an echo value, but I can't figure out how to echo it.

For example, let's say you're surfing MySite2/World - where $MySiteID = 'PX' - and you click the following link:

Code:
<a href="javascript:;" onClick="MM_openBrWindow('http://www.mysite1.com/Aids/World_Children/Can.php?MySiteID=<?php echo $MySiteID; ?>','IRCAN','scrollbars=yes,resizable=yes,width=175,height=250')">PopUp</a>
When World_Children/Can.php opens, I want it to inherit the $MySiteID value (PX).

Or if I visited MySite3/World - $MySiteID = 'Three' - and clicked a similar link, then the same popup (World_Children/Can.php) would open. But this time, it would assume the value $MySiteID = 'Three.'

So it looks like my JavaScript link is already set up to do just that. I just don't understand what I have to do on the other page (Can.php) to copy and display that value.

Thanks.