Approval Procedure Query

Dear All,

I have created an approval procedure on PO based on total amount as below.

SELECT 'TRUE' where exists (

  SELECT T0.CardCode FROM OCRD T0

  WHERE T0.CardCode=$[$4.0.0] AND ($[opor.doctotal.number]-$[opor.vatsum.number]) between 0 and 250000)

The requirement is to check the amount based on currency, for example:

a. if AED then the amount is between 0 and 100000

b. if EUR then it's between 10000 and 50000

c. etc.

How should i proceed with it?  Please advise.

Note: LC - USD

Thanks and Regards,

Lailus