About magritte for XML serialization

Hi lukas I wanted to know this was possible to specify how an field should be saved and reloaded. For example I wanted to save a date and reload it. I added MADateDescription>>parseString: aString ^ self parseString: aString protected: [ aString asDate ]. to MADateDescription :) but I have the impression that been able to specify at the description level the way the values are saved and filed in would make sense. I checked on my old version of MA, but I could not find how the MADescription itself was describing the condition because it would be the same process may be been able to specify a block or a selector for each of the action would be cool. Lukas? Stef