i guess then they are redacting any info they consider sensitive and secret, because it relates to other government bodies such as CSIS, etc. Basically they don't want you to know anything about their communication with those parties.
21 (1) The head of a government institution may refuse to disclose any record requested under this Act that contains
(a) advice or recommendations developed by or for a government institution or a minister of the Crown,
(b) an account of consultations or deliberations in which directors, officers or employees of a government institution, a minister of the Crown or the staff of a minister participate,
(c) positions or plans developed for the purpose of negotiations carried on or to be carried on by or on behalf of the Government of Canada and considerations relating thereto, or
(d) plans relating to the management of personnel or the administration of a government institution that have not yet been put into operation,
if the record came into existence less than twenty years prior to the request.
Marginal note:Exercise of a discretionary power or an adjudicative function
(2) Subsection (1) does not apply in respect of a record that contains
(a) an account of, or a statement of reasons for, a decision that is made in the exercise of a discretionary power or an adjudicative function and that affects the rights of a person; or
(b) a report prepared by a consultant or an adviser who was not a director, an officer or an employee of a government institution or a member of the staff of a minister of the Crown at the time the report was prepared.