to facilitate text editing; a file that defines these byte=letter relationships is called a "table" file. Other games use simple text compression techniques (such as byte pair encoding, also called dual tile encoding or DTE, in which certain combinations of two or more letters are encoded as one byte) which a suitably equipped hex editor can facilitate editing. A hex editor is the tool of choice for editing things such as character/item properties, if the structure and location of this data is known and there is no game-specific editor for the game that can edit this information. Some intrepid hackers also perform level editing with a hex editor, but this is extremely difficult (except on games whose level storage format closely resembles how it is presented in a hex editor). Graphics editing Another basic hacking skill is graphics hacking, which is changing the appearance of the game's environments, characters, fonts, or other such things. The format of graphics data varies from console to console, but most of the early ones (NES, Super NES, Game Boy, etc.) store graphics in tiles, which are 8x8-pixel units of data, which are arranged on-screen to produce the desired result. Editing these tiles is also possible with a hex editor, but is generally accomplished with a tile editor (such as Tile Layer or Tile Molester), which can display the ROM data in a graphical way, as well as finding and editing tiles. Graphics hacks can range from simple edits (such as giving Mario an afro or Luigi a golf club) to "porting" characters from one game to another (such as creating pixelated "retro-styled" sprites of later generation Pokémon for use in Generation I-III Pokémon games), to full-blown thematic changes (usually with accompanying palette changes; see below). More sophisticated graphics hacking involves changing more than just tiles and colors, but also the way in which the tiles are arranged, or tile groups generated, giving more flexibility and control over the final appearance. This is accomplished through hex editing or a specialized tool (either for a specific game or a specific system). A good example of a graphics hack is the incomplete Pokémon Torzach, a hack of Pokémon FireRed which attempted to add a whole new generation of Pokémon and tiles to the game. The hack has since been discontinued, but it still serves as a good example on what can be achieved with the tools available.