Again, it's a document within the executive government.
Essentially, as individual ministers develop proposals that then come to a cabinet committee for consideration, the finance department takes the lead if it's a spending thing, producing a green brief, which is two things in one. It's a summary of the proposals and it's a commentary on the proposals with recommendations, which are usually agreed to, but not always, among the three central agencies—the finance and treasury departments and the prime minister—but Finance takes the running on preparing those things.
That document goes into a cabinet committee. It is used as the agenda for cabinet consideration, or for cabinet committee consideration, but it is never intended for public consumption. It is part of the deliberative process of cabinet.