looking for product_id to implement 3rd party tool in my site

hi,
i'm rather new to zencart, the client is using version .
what puzzles me though, is how i would have to go about requesting the product id from the querystring of the form handler.
the product attributes form submits to this url to add to cart.
where can i add the global include to the form handler, and how will i be able to get the subvalues if the form action is as follows:
http://canopyxchange.za.net/index.php?main_page=product_info&cPath=36_170&products_id=312&number _of_uploads=0&action=add_product
i'm guessing it's a subarray, so would the following work to get the products_id querystring "subvalue" of main_page?

PHP Code:

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$prodid = $_GET["main_page"]["products_id"]; 


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after careful concideration, i believe & in the action url is converted to & by the browsers. i would therefore only have to

PHP Code:

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$prodid = $_GET["products_id"]; 


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