VendorSpecificDataKey
The BizTalk RFID document doesn't seem to keep up with the implementation; the following code is taken from "How to Implement an Event Handler Method" page of the help documentation, it's a part of the custom hadler method:
// Return this info for next event handler.
string message = string.Format("The tag with id {0} has shipped", tagReadEvent.GetId());
VendorSpecificDataKey key = new VendorSpecificDataKey("Microsoft", "Test");
tagReadEvent.VendorSpecificData[key] = message;
Coding my own custom handler, I noticed that the VendorSpecificDataKey is no being used anymore and that a 'string' is used as a key for the
tagReadEvent.VendorSpecificData["key"] = message;

