How to resolve the discount condition expression xml.

Hi,
   I got the condition expression of discount by override the 
CSFLoadDiscount StoreProcedure.

   The expression xml structure is pretty simple, seems each line of 
expression is corresponding to one clause. But the property ID looks a
little 
different from the product property used within the product object. I
wonder 
is there any conversion rule or tables so I can use to do the property 
conversion. Or is there any object I can use to resolve this expression
xml

below is the example of the example of condition expression
<CLAUSE OPER="contains" 
xmlns="http://schemas.microsoft.com/CommerceServer/2004/02/Expressions">
	<PROPERTY ID="Product._product_Manufacturer" TYPE="STRING"
MULTIVAL="false" 
/>
	<IMMED-VAL TYPE="STRING"><VALUE>123</VALUE></IMMED-VAL>
</CLAUSE>