Generic datasource based on function module initialization

Hi all,

I've created a generic delta enabled datasource based on function module.

I used AEDAT as my field for the delta.

My question is: how can I filter records with AEDAT >= 01.01.2013 in the initialization data load?

This field is not available for selection when creating the datasource, therefor cannot be used during extraction:

Thanks,

Hagit