What is the test for describing privileged documents?

In Creaser v. Warren (1987), 36 D.L.R. (4th) 147, 77 N.S.R. (2d) 429, 191 A.P.R. 429 (C.A.), the headnote [D.L.R.] reads in part: While the description of documents for which privilege is claimed need not be so detailed that it discloses the contents of the document in a manner that would destroy its privilege, the description must be sufficient to enable the court to make a prima facie decision whether a likely claim for privilege exists. The description should have sufficient detail to reveal the nature of the documents to the opposing party and should identify the status of the receiver and sender, their relationship to the party and to the action, and the basis upon which the claim for privilege is grounded.