Record level currency conversion

Hi all,

Is it possible with NW 7.0 to perform currency conversion dynamically according to the rate at a given transaction time? meaning that a given query may use many different rates for the same FROM-TO combination

Ex:

DATE -

KRW--

12/1/2008--

70

01/1/2009--

60

Right now all I can see is that I can use one rate based on one given date for a query...am I missing something?