sideview item availability
The Availability Editor allows you to control which items appear in a given side-view area.
Many areas in the vanilla game feature additional items or doors which are not present when the player enters that area. The original purpose of this was to be able to re-use a sideview map in different parts of the game.
The game tracks items by screen, so each screen in the game has a flag which controls whether or not an item is available on that screen.