There are some very fine points. This is a very controversial exemption that allows, on a discretionary basis, for institutions to withhold information that is deemed to be considered advice to the minister. So this is not to be confused with a cabinet confidence, which is an entirely separate issue.
Advise to the minister can be interpreted very broadly or it can be interpreted very narrowly. There are provisions within section 21 that basically say if you are talking about a program or a policy that has not yet taken effect, you can withhold information pertaining to the advisability of doing so. It drives people crazy to see a section 21 exemption because the latitude for interpretation is so incredibly great.