anchor.diff:      };
     };
   
  +  ipv6PrefixOptions = {
  +    options = {
  +      ipv6PrefixConfig = mkOption {
  +        default = {};
  +        example = { Prefix = "fd00::/64"; };
  +        type = types.addCheck (types.attrsOf unitOption) checkIpv6Prefix;
  +        description = ''
  +          Each attribute in this set specifies an option in the
  +          <literal>[IPv6Prefix]</literal> section of the unit.  See
  +          <citerefentry><refentrytitle>systemd.network</refentrytitle>
  +          <manvolnum>5</manvolnum></citerefentry> for details.
  +        '';
  +      };
  +    };
  +  };
  +
   
     networkOptions = commonNetworkOptions // {
   
  
positive.code:             ${attrsToSection def.ipv6PrefixDelegationConfig}
  
            ''}
            ${optionalString (def.dhcpServerConfig != { }) ''
              [DHCPServer]
              ${attrsToSection def.dhcpServerConfig}
  
negative.code:     (assertMinimum "DNSLifetimeSec" 0)
    ];
  
    checkIpv6Prefix = checkUnitConfig "IPv6Prefix" [
      (assertOnlyFields [
        "AddressAutoconfiguration"  "OnLink"  "Prefix"
        "PreferredLifetimeSec" "ValidLifetimeSec"
      ])
      (assertValueOneOf "AddressAutoconfiguration" boolValues)
      (assertValueOneOf "OnLink" boolValues)
      (assertMinimum "PreferredLifetimeSec" 0)
      (assertMinimum "ValidLifetimeSec" 0)
    ];
  
  
    checkDhcpServer = checkUnitConfig "DHCPServer" [
      (assertOnlyFields [
        "PoolOffset" "PoolSize" "DefaultLeaseTimeSec" "MaxLeaseTimeSec"
  