A set of named specialized configurations. These can be used to extend your base configuration with additional settings. For example, you can have specialisations named "light" and "dark" that apply light and dark color theme configurations.
For example, to activate the "dark" specialisation, you can first look up your current Home Manager generation by running
$ home-manager generations | head -1 2022-05-02 22:49 : id 1758 -> /nix/store/jy…ac-home-manager-generation
$ /nix/store/jy…ac-home-manager-generation/specialisation/dark/activate Starting Home Manager activation …