Why do some of my XBee Network devices have an unspecified Product Type, while others show valid information?

The "Product Type" column shown below is part of the Network View of the XBee Devices table from a ConnectPort X8 gateway.  The table is located at Configuration > XBee Network within the Gateway's Web User Interface.  "Product Type" is actually a user-configurable AT parameter on each XBee module (including the Coordinator module in the CP-X8 shown), which can be used to help identify various device types on an XBee Network.

• ConnectPort X gateways will have their embedded XBee-PRO module listed as "X# Gateway" (# is the model number of ConnectPort X).
• XBee and XBee-PRO adapters also have the Adapter type pre-set in the factory.
• In XBee and XBee-PRO RF Modules, the DD parameter is unconfigured.

For anyone wanting further information or a listing of all the DD parameters, details can be found here.