2.9 Path When an SD Card is Used

[FearTheTJ]

The maximum save data size is 32 MB. Currently, the only means to save larger data is to use an SD Card.
The Wii U SDK uses FAT32 for file systems on SD Cards. The application must handle removal of the media and other similar errors, because the auto error handling feature does not work when accessing FAT32. Also, take due care when using FAT32 since data corruption, data overwrites, and attribute changes at the file level can easily occur.
When saving data to an SD Card, use the following directory structure to avoid name collisions with files and directories from other applications:
\private\Nintendo Wii U\app
The reason for restricting the directory structure is to avoid unintentional name collisions with other applications; therefore, if you have obtained consent from one or more other applications, it is permissible to choose the Initial Code of one of the applications and unify that portion of the directory structure so that all the involved applications use the same Initial Code folder.
When doing so, check to make sure it does not cause any issues on any of the involved applications.

2.9.1 Handling Writing Data to SD Cards

Guideline Item
Applications which save data to an SD Card must only write to the specified folder.
Test Method
Create data on an SD Card.
Insert the SD Card into a computer and check the location at which the data is saved.
Pass/Fail Determination
If the data is used by a single application:
In step 2, the data has been created in the following folder on the SD card.
\private\Nintendo Wii U\app
If the data is used by multiple applications:
In step 2, the data has been created in the following folder on the SD card.
\private\Nintendo Wii U\app
Software to Be Tested
Applications that save data to an SD Card.