Files to look at:
This example demonstrates the capability to provide XML serialization of custom parameter types.
In particular, it shows how you can save a report, along with its parameters of the System.Enum type, to XML file.
To do this, override the ReportStorageExtension class, and register a custom ReportDesignExtension, which implements the data source serialization functionality.
To serialize custom objects and properties, specify the XtraSerializableProperty attribute with the XtraSerializationVisibility.Reference parameter (this parameter defines whether or not an object should be serialized by a reference).