Section 29(4)

…

(4) If—

(a) an application is expressed to relate to all documents, or to all documents of a stated class, that contain information of a stated kind or relate to a stated subject matter; and

(b) it appears to the agency or Minister that all of the documents to which the application relates are exempt documents;

the agency or Minister may refuse to deal with the application without having identified any or all of the documents.

(5) The notice of the agency's or Minister's decision under subsection (4) to refuse to deal with an application must identify the provision under which the documents are exempt documents.