1. A product to link a graphical user interface (GUI) element type to a GUI element in a GUI, the product comprising: a computer-readable memory; a reference graphical user interface (GUI) type model stored in the computer-readable memory; builder logic stored in the computer-readable memory and executable by a processor, the builder logic comprising: element selection logic that when executed by the processor, causes the processor to obtain a GUI element selection specifying a selected GUI element in a GUI of a GUI application (GAP); retrieval logic that when executed by the processor causes the processor to retrieve, from the reference GUI type model, a GUI element type selection list of available GUI element types; selection logic that when executed causes the processor to obtain a GUI element type selection specifying a selected GUI element type from the GUI element type selection list of available GUI element types; and association logic that when executed by the processor causes the processor to create a GUI element type mapping that links the selected GUI element type to the selected GUI element in the GUI; message creation logic in the computer-readable memory that when executed by the processor causes the processor to build a GUI element type specification message that signifies that data within the message specifies a type mapping for a GUI element; and communication logic in the computer-readable memory that when executed by the processor causes the processor to create a GUI element type specification in a metadata repository by sending the GUI element type specification message to the metadata repository.