Specifies the COM object associated with this MIME type. You can select a COM object from the drop-down list box. The drop-down list box shows the globally unique identifier (GUID) for each COM object included in your installer project.
Remarks
Associating a MIME type with a COM object indicates this COM object acts on this MIME type. You can also use the property as an aid in linking the MIME type to its program identifier (ProgID).