Need to create a Shipping Exempt item

I need to make a few seminar registrations shipping cost exempt. Of the add to cart code below, what do I change?

Also, is there a list of these codes and what each will accept as a variable?

Thanks

<form action="https://www.calcourt.org/asp-cgi/shop1.aspx" method='POST' name='scform'>
           <div align="left">
             <input type='hidden' name='part' value='SantaCruz'>
             <input type='hidden' name='description' value='Santa Cruz Training Day, Member'>
             <input type='hidden' name='price' value='40.00'>
             <input type='hidden' name='prodsize' value=''>
             <input type='hidden' name='weight' value=''>
             <input type='hidden' name='units' value='ea.'>
             <input type='hidden' name='taxed' value='No'>
             <input type='hidden' name='taxed2' value='Yes'>
             <input type='hidden' name='extratax' value=''>
             <input type='hidden' name='postpone' value='False'>
             <input type='hidden' name='prod_shipping' value='0.00'>
             <input type='hidden' name='prod_handling' value=''>
             <input type='hidden' name='merchantcode' value=''>
             <input type='hidden' name='discountpath' value='discountcode.gif'>
             <input type='hidden' name='code1' value=''>
             <input type='hidden' name='code2' value=''>
             <input type='hidden' name='code3' value=''>
             <input type='hidden' name='code4' value=''>
             <input type='hidden' name='discounted' value='No'>
             <input type='hidden' name='cdiscount1' value=''>
             <input type='hidden' name='cdiscount2' value=''>
             <input type='hidden' name='cdiscount3' value=''>
             <input type='hidden' name='cdiscount4' value=''>
             <input type='hidden' name='volume1' value=''>
             <input type='hidden' name='volume2' value=''>
             <input type='hidden' name='volume3' value=''>
             <input type='hidden' name='volume4' value=''>
             <input type='hidden' name='volume5' value=''>
             <input type='hidden' name='volume6' value=''>
             <input type='hidden' name='discount1' value=''>
             <input type='hidden' name='discount2' value=''>
             <input type='hidden' name='discount3' value=''>
             <input type='hidden' name='discount4' value=''>
             <input type='hidden' name='discount5' value=''>
             <input type='hidden' name='discount6' value=''>
             <input type='hidden' name='upsell' value=''>
             <input type='hidden' name='upsellpath' value='related.gif'>
             <input type='hidden' name='minqty' value=''>
             <input type='hidden' name='divqty' value=''>
             <input type='hidden' name='buyqty' value=''>
             <input type='hidden' name='freeqty' value=''>
             <input type='hidden' name='pricemin' value=''>
             <input type='hidden' name='requiresku' value=''>
             <input type='hidden' name='payloadurl' value='None'>
             <input type='hidden' name='qtyimg' value='./mall/QTYButton.gif'>
             <input type='hidden' name='quantityon' value='True'>
             <input type='hidden' name='addimg' value='./mall/ADDButton.gif'>
             <input type='hidden' name='checkout' value='../asp-cgi/shop1.aspx'>
             <input type='hidden' name='optionon' value='False'>
             <input type='hidden' name='optionsize' value='3'>
             <input type='hidden' name='optionname' value='./mall/option.gif'>
             <input type='hidden' name='includeon' value='False'>
             <input type='hidden' name='include' value='include.htm'>
             <input type='hidden' name='sameline' value='False'>
             <input type='hidden' name='auction' value='False'>
             <input type='hidden' name='pricepath' value='auction.gif'>
             <input type='hidden' name='pricesize' value='3'>
             <input type='hidden' name='bid' value='False'>
             <input type='hidden' name='bidpath' value='BIDbutton.gif'>
             <input type='hidden' name='expire' value='False'>
             <input type='hidden' name='expiredate' value=''>
             <input type='hidden' name='expiremessage' value=''>
             <input type='hidden' name='emailfriend' value='False'>
             <input type='hidden' name='emailfriendpath' value='emailfriend.gif'>
             <input type='hidden' name='codesize' value='0'>
             <img src='./mall/QTYButton.gif' alt='Quantity:' align='absmiddle' name='QtyImg' width="36" height="21">
             <input type='text' size='3' name='Quantity' value='1'>
             <input src='./mall/ADDButton.gif' name='ADDButton' alt='Add Item(s):' type='image' align='absmiddle' value='ADD' width="64" height="16">
           </div>
      </form></td>