The 

 features a file system, as detailed in File System. The files in the file system can contain arbitrary data, and are typically used to store non-volatile configuration parameters.

The 02-gpio_net and 02-spi_net sample applications (detailed in the GPIO and SPI pages, respectively) use a file to store the parameters entered by the user.

The format of the file is determined by a struct, and the configuration file for each application has a different name.

When the device boots, the configuration is read from the file, and stored in RAM for use during execution. Each time the user changes the configuration, the updated data is written back to the file.