WCF Ria DateTime http query serialization

Question

Hi, I need to call a wcf ria domain service and I want to use filtering. I need to code the http url explicitly myself. I found the following example on the net (http://jasonharper.wordpress.com/2009/09/27/ria-services-under-the-hood-part-2-query-operations/):

https: //..../SnagAllPeeps?$where=(Age%3e35)

This will call SnagAllPeeps such that all returned items have an Age property with a value greater than 35. What I need is to do essentially the same for properties of type DateTime. But how are these serialized? I tried something like:

https: //..../SnagAllPeeps?$where=(PostedOn%3e0001-01-01T00%3a00%3a00)

but this does not work. Any idea what the right format is or how I can find out?