An archive which contains a number of DDS texture files.
These are usually found inside [SDHC] or [PACH] files, and the textures can be extracted or injected using several [Mod Tools] such as PacTool or X-Packer. Both PacTool and X-Packer can also create new Texture Archives.
Typically, textures need to be the same file size as the texture inside the archive in order to be injected back in. A workaround for this is to create a new Texture Archive with all the textures, including the new ones.
For character PACs, textures are contained inside the 000A and 000C files.
For arena PACs, textures are typically inside the 03E8 file.