Return/set the source used by WebX for the MIME Content Type returned to the client in the HTTP header. Allowable sources are: Registry (0), File (1), Internal (2).
If ContentTypeSource = Registry, the file type extensions in HKEY_CLASSES_ROOT are searched and the "Content Type" value is used to return the content type.
If ContentTypeSource = File, the file specified in ContentTypeSourceFile is used to search for MIME types associated with file extensions. If ContentTypeSource = Internal, an internal table containing approximately 200 MIME types is used for the lookup.