anchor.diff:    fsType ? "ext4"
   
   , # Filesystem label
  -  label ? "nixos"
  +  label ? if onlyNixStore then "nix-store" else "nixos"
   
   , # The initial NixOS configuration file to be copied to
     # /etc/nixos/configuration.nix.
  
positive.code:          (attrs: ((attrs.user  or null) == null)
                == ((attrs.group or null) == null))
           contents;
  
  with lib;
  
  
negative.code:         tune2fs -T now -c 0 -i 0 $rootDisk
        ''}
      ''
    );
  in
    if onlyNixStore then
      pkgs.runCommand name {}
        (prepareImage + moveOrConvertImage + postVM)
    else buildImage
  