|CC1 Index||54, 55, 56|
Not used tiles, also called Unused tiles, are tiles with the index of 54, 55, and 56. These tiles have the same properties of invisible walls. These tiles are not seen in CC1, but they occasionally are seen in custom level sets. They have no purpose within the game, and because of this, David Stolp created a patch which turns the unused 56 tile into an ice block.
Since they are never used in the game, and therefore never mentioned in it or in the help file, the naming of these tiles was left up to the creator of level editors. In ChipEdit, all three tiles are referred to as NOT USED. In Chip's Workshop these tiles are simply called invalid. In CCEdit, they also referred to as Not used. However, unlike in Chipedit which uses the actual appearance of the tile within the editor, CCEdit uses these graphics for the tiles.
The numbers 36, 37, and 38 refer to these tiles' indexes in hex. These graphics are also used in CCLD. However, CCLD refers to them as Unused and also replaces the unused 56 (38 in hex) with the ice block. In Tile World, the unused tile is Lynx death explosion.