An invalid tile can be a single tile, a combination of a non-transparent tile other than a block and any tile buried underneath it, or anything buried under an item. These invalid combinations are nonexistent in the Lynx version, so Tile World's Lynx does not allow play in levels with invalid tiles. However, the MS version was more sloppily coded and did not restrict the use of invalid tiles. Invalid tiles are present in CCLP2 and many custom level sets, and a combination is distinguished in ChipEdit using the following: