CN07-4 is a notice to upgrade your software by MAch 31st 2007. For all Exporters who use the automated Export Declaration systems, take note of the notice.
"In CAED 2007 version 7.10, the container number field now accepts the 11-character international standard. Exporters are reminded that a complete container number is required to be reported to the Canada Border Services Agency (CBSA). Failure to provide a complete and/or accurate container number may result in the issuance of Administrative Monetary Penalty System penalties."
Notice can be downloaded here