The RevPi Flat modules are based on a Linux operating system from the Raspberry Pi Foundation. This has a code name, like “Stretch” for example. It is important to specify the code name of your operating system when exchanging information with other RevPi users.
Starting from the “Jessie” version, you can retrieve the code name and release date of the operation system at delivery:
In this case it is a Flat system from November 5, 2020.