WFS is the filesystem used on the Wii USB Memory device. It was designed to store titles, much like the NAND, but was ultimately only used by Dragon Quest X. It is possible, but unconfirmed, that this is the exact same filesystem used for external devices on the Wii U.
A standard Wii USB Memory device has 2 directories in the root:
WFS titles have different directories than NAND titles.
- /_patch: Holds updates/DLC
- /content: Holds main title contents. Unlike on the NAND, all WFS contents are ARCs that are extracted on install, and the boot content is now
- /meta: Holds TMDs. It is not currently known if both the main TMD and patch TMDs are stored here.
- /save: Presumably holds save data. IOS does not place any known files here.