Since the SSP version is specific to each XML file within the SSP, it is possible (and allowed) for an SSP file to contain XML files that are different SSP versions (i.e. there is no restriction that all XML files within an SSP file must be the same version). I think it would be a good idea to explicitly state this to ensure that tool implementations take this into consideration. We should also mention that since SSP versions are backward compatible, tools can safely load an SSP file using the latest SSP version without needing to be concerned about the specific SSP version(s) referenced by the internal XML documents.