anchor.diff:        default = null;
         example = { system = "aarch64-linux"; config = "aarch64-unknown-linux-gnu"; };
         description = ''
  +        Systems with a recently generated <literal>hardware-configuration.nix</literal>
  +        may instead specify <emphasis>only</emphasis> <option>nixpkgs.buildPlatform</option>,
  +        or fall back to removing the <option>nixpkgs.hostPlatform</option> line from the generated config.
  +
           Specifies the platform for which NixOS should be
           built. Specify this only if it is different from
           <code>nixpkgs.localSystem</code>, the platform
  
positive.code:       defaultText = literalExpression
          ''(import "''${nixos}/../lib").lib.systems.examples.aarch64-multiplatform'';
        description = ''
          Specifies the platform on which NixOS should be built. When
          <code>nixpkgs.crossSystem</code> is unset, it also specifies
          the platform <emphasis>for</emphasis> which NixOS should be
  
negative.code:     system = mkOption {
        type = types.str;
        example = "i686-linux";
        default =
          if opt.hostPlatform.isDefined
          then
            throw ''
              Neither ${opt.system} nor any other option in nixpkgs.* is meant
              to be read by modules and configurations.
              Use pkgs.stdenv.hostPlatform instead.
            ''
          else
            throw ''
              Neither ${opt.hostPlatform} nor or the legacy option ${opt.system} has been set.
              You can set ${opt.hostPlatform} in hardware-configuration.nix by re-running
              a recent version of nixos-generate-config.
              The option ${opt.system} is still fully supported for NixOS 22.05 interoperability,
              but will be deprecated in the future, so we recommend to set ${opt.hostPlatform}.
            '';
        defaultText = lib.literalMD ''
          Traditionally `builtins.currentSystem`, but unset when invoking NixOS through `lib.nixosSystem`.
        '';
        description = ''
          This option does not need to be specified for NixOS configurations
          with a recently generated <literal>hardware-configuration.nix</literal>.
  
          Specifies the Nix platform type on which NixOS should be built.
          It is better to specify <code>nixpkgs.localSystem</code> instead.
          <programlisting>
  