Nixos-rebuild list-generations

The command nixos-rebuild list-generations produces an output in the following format:

Generation  Build-date           NixOS version            Kernel  Configuration Revision  Specialisation
19 current  2023-12-27 20:38:59  23.11.2217.d02d818f22c7  6.6.8                           *

Is there any documentation what the columns mean?
I do not know what Configuration Revision and Specialisation want to tell me.

Thanks for your help.

Specialisations are basically extra configurations that are built in addition to the default one. The table tells you that you don’t currently use any. Tweag have a nice blog post explaining them in more detail: Introduction to NixOS specialisations

The configuration revision is literally what it says on the tin, the git commit from which the generation was built: NixOS Search

I think you need to set it manually to get a value in there though.