Dynamic Descriptors

Hi, I'm wondering if Dynamic Descriptors are available in the DirectPost option of Moneris? We have one Merchant Account but would be interested in using different descriptors for different items that we sell online. (Different Stores under the same Umbrella company if you will)

Is there documentation somewhere that outlines all of the available variables you can send in your HTML Post? I know I had one years ago when I first developed our sites but I've looked around for a more recent version and can't seem to find it posted anywhere.

Thanks.