MSI Factory
This dialog allows you to create file associations for the current file. A file association allows you to register your program as the handler for specific file types. During installation, the appropriate registry keys will be created for your file associations.
Click the Add button to open the File Association Properties dialog and configure a new file association.
MSDN Online: Extension Table
MSDN Online: Verb Table
WiX Help File: Extension Element
WiX Help File: Verb Element