An NFP tag includes two data regions: a shared region and an application-specific region.
The shared region stores information about the amiibo itself, such as the character ID, and registration information. Any NFP-compatible application can read from the shared region, but only the amiibo Settings system application can write to the region.
The application-specific region can hold up to 216 bytes of data. The application can decide what data to store. However, only one application can store data at a time. Data in the application-specific region can only be read by an application with the same access ID as the application that created the region. To overwrite the data in the application-specific region, prompt the user to delete the data using the amiibo Settings application and then create a new region.