TXTR (File Format)
The TXTR format is, as you can probably tell from the name, for textures. There are two versions of the format. The first one was in use for a very long time, with absolutely no changes between games whatsoever, all the way from the Metroid Prime kiosk demo up to Donkey Kong Country Returns. It was finally overhauled when the hardware jump from the Wii to the Wii U was made, due to the substantial hardware changes and the new image formats used by GX2.