That would be referencing this, which basically means they redacted it from your GCMS notes for the following reason.
http://www.oic-ci.gc.ca/eng/inv_inv-gui-ati_gui-inv-ati_section_16.aspx
16(1)The head of a government institution may refuse to disclose any record requested under this Act that contains
(c) information the disclosure of which could reasonably be expected to be injurious to the enforcement of any law of Canada or a province or the conduct of lawful investigations, including, without restricting the generality of the foregoing, any such information
- Relating to the existence or nature of a particular investigation,
- that would reveal the identity of a confidential source of information, or
- that was obtained or prepared in the course of an investigation;
Basically it means that there was some sort of criminal/security/etc check done and they will not disclose the organization/government/entity that they used to check on it because that information is exempt from having to be disclosed due to the rule above