ProgId (min: 0, max: unbounded): The version-independent ProgId must be the first child element of actual ProgId. Nesting other ProgId elements within the Version-independent ProgId will create COM+ aliases, see http://support.microsoft.com/kb/305745 for more information.
Extension (min: 0, max: unbounded): Extensions that refer to this ProgId
For an advertised ProgId, the Id of an Icon element. For a non-advertised ProgId, this is the Id of a file containing an icon resource.
IconIndex
Integer
NoOpen
String
Specifies that the associated ProgId should not be opened by users. The value is presented as a warning to users. An empty string is also valid for this attribute.