anchor.diff:        '';
       };
   
  -    isoImage.volumeID = pkgs.lib.mkOption {
  +    isoImage.volumeID = mkOption {
         default = "NIXOS_BOOT_CD";
         description = ''
           Specifies the label or volume ID of the generated ISO image.
  
positive.code:       '';
      };
  
      isoImage.contents = pkgs.lib.mkOption {
        example =
          [ { source = pkgs.memtest86 + "/memtest.bin";
              target = "boot/memtest.bin";
  
negative.code: 
    # We need squashfs in the initrd to mount the compressed Nix store,
    # and aufs to make the root filesystem appear writable.
    boot.extraModulePackages = (optional 
      (! config.boot.kernelPackages.kernel.features ? aufs) 
      config.boot.kernelPackages.aufs);
    boot.initrd.extraKernelModules = ["aufs" "squashfs"];
  