This directory contains netif drivers for lwIP. These drivers are *not* always updated when something changes in lwIP, meaning they might or might not work with a version of lwIP different than they were written for. Therefore, the directory structure indicates the version of lwIP used when the drivers were written. If there is any other versioning which is of interest (e.g. for which OS or OS version), there should be an extra readme file in the driver directory. Usually, driver should continue to work without changes throughout different minor releases in one major release (e.g. a driver written for 1.3.0 should work with 1.3.1). Therefore, there are only directories for major releases.