about attribute... (trying to implement a "DataContractSerializer" functionality)

[Lloyd Dupont]

>From the book I was under the impression that there could be user defined 
attribute.
I wonder if this has been implemented?

My problem: I try to implement a simplistic "DataContractSerializer" (as in
http://msdn.microsoft.com/en-us/library/SYSTEM.RUNTIME.SERIALIZATION.DATACONTRACTSERIALIZER(v=vs.100,d=lightweight).aspx
)
Which, basically, use reflection / introspection to save on a permanent 
format whatever properties / fields has been marked as being important. I.e. 
attribute driven serialization if I might say...

Is there such a thing?
Any tip on how to go on implementing something.. similar?