anchor.diff:          example = [ { type = "svn"; url = "https://svn.nixos.org/repos/nix/nixos/branches/stdenv-updates"; target = "/etc/nixos/nixos-stdenv-updates"; }
                       { type = "git"; initialize = ''git clone git://mawercer.de/nixos $target''; update = "git pull origin"; target = "/etc/nixos/nixos-git"; }
                     ];
  -        description = "The NixOS repository from which the system will be build. 
  -                       nixos-checkout will update all working copies of the given repositories,
  -                       nixos-rebuild will use the first item which has
  -                       the attribute default = true falling back to the
  -                       first item. The type defines the repository tool added
  -                       to the path. It also defines a \"valid\" repository.
  -                       If the target directory already exists and it's not
  -                       valid it will be moved to the backup location
  -                       <filename>\${dir}-date</filename>.
  -                       For svn the default target and repositories are
  -                       <filename>/etc/nixos/nixos</filename> and
  -                       <filename>https://svn.nixos.org/repos/nix/nixos/trunk</filename>.
  -                       For git repositories update is called after
  -                       initialization when the repo is initialized.
  -                       The initialize code is run from working directory
  -                       dirname \$target and should create the directory
  -                       <filename>\$target<filename>. (<command>git clone url nixos/nixpkgs/services</command> should do)
  -                       For the executables beeing used see <option>repoTypes</option>
  -                       ";
  +        description = ''
  +          The NixOS repository from which the system will be built.
  +          <command>nixos-checkout</command> will update all working
  +          copies of the given repositories,
  +          <command>nixos-rebuild</command> will use the first item
  +          which has the attribute <literal>default = true</literal>
  +          falling back to the first item. The type defines the
  +          repository tool added to the path. It also defines a "valid"
  +          repository.  If the target directory already exists and it's
  +          not valid it will be moved to the backup location
  +          <filename><replaceable>dir</replaceable>-date</filename>.
  +          For svn the default target and repositories are
  +          <filename>/etc/nixos/nixos</filename> and
  +          <filename>https://svn.nixos.org/repos/nix/nixos/trunk</filename>.
  +          For git repositories update is called after initialization
  +          when the repo is initialized.  The initialize code is run
  +          from working directory dirname
  +          <replaceable>target</replaceable> and should create the
  +          directory
  +          <filename><replaceable>dir</replaceable></filename>. (<command>git
  +          clone url nixos/nixpkgs/services</command> should do) For
  +          the executables used see <option>repoTypes</option>.
  +        '';
         };
   
         nixpkgs = mkOption {
  
positive.code:     };
  
      repoTypes = mkOption {
          default = {
            svn = { valid = "[ -d .svn ]"; env = [ pkgs.coreutils pkgs.subversion ]; };
            git = { valid = "[ -d .git ]"; env = [ pkgs.coreutils pkgs.git pkgs.gnused /*  FIXME: use full path to sed in nix-pull */ ]; };
          };
          description = "defines PATH environment and when directory is considered beeing a valid repository.
                If it's not it's moved to a backup directory";
      };
  
      manifests = mkOption {
  
negative.code:         default = [];
          example = [ "proxy_connect" { name = "php5_module"; path = "${pkgs.php}/modules/libphp5.so"; } ];
          description = ''
            Specifies additional Apache modules.  These can be specified
            as a string in the case of modules distributed with Apache,
            or as an attribute set specifying the
            <varname>name</varname> and <varname>path</varname> of the
            module.
          '';
        };
  
  