This is directly related to how estimates work. When we get the main estimates, which is how we start the year, any department that is going to spend money, which is all departments, would be on that list. As the year goes on, if departments get Treasury Board approval to spend new money and indicate they are capable of spending it this year, because we do resource departments year by year, you come into supplementary estimates. Supplementary estimates (B) is our biggest, but there are certain departments that had no items where they were requesting additional funds, so they are not included here. This means that they're status quo.
Evidence of meeting #35 for Government Operations and Estimates in the 41st Parliament, 2nd Session. (The original version is on Parliament’s site, as are the minutes.) The winning word was money.
A video is available from Parliament.