DTD ----------+
              |
config file --+ -- DOM/SAX Parser --> Python object
              |
Scheme -------+


DTD ----------+
              |
Python object --> XSLT-like transformation --> named.conf
              |
Scheme -------+

<xs:attributeGroup name="zone" minOccurs=0 maxOccurs="unbounded">
  <xs:choice>
    <xs:attribute name="allow-notify" minOccurs="0" maxOccurs="1">
    <xs:attribute name="allow-query" minOccurs="0" maxOccurs="1">
    <xs:attribute name="allow-query-on" minOccurs="0" maxOccurs="1">
    <xs:attribute name="allow-recursion" minOccurs="0" maxOccurs="1">
    <xs:attribute name="allow-recursion-on" minOccurs="0" maxOccurs="1">
    <xs:attribute name="allow-transfer" minOccurs="0" maxOccurs="1">
    <xs:attribute name="allow-update" minOccurs="0" maxOccurs="1">
    <xs:attribute name="allow-update-forwarding" minOccurs="0" maxOccurs="1">
    <xs:attribute name="forwarders" minOccurs="0" maxOccurs="1">
    <xs:attribute name="server-addresses" minOccurs="0" maxOccurs="1">
    <xs:attribute name="server-names" minOccurs="0" maxOccurs="1">
    <xs:attribute name="update-policy" minOccurs="0" maxOccurs="1">
  </xs:choice>
</xs:attributeGroup name="zone">


<xs:attributeGroup name="clause_zone_or_view">
  <xs:complexType name="zone_or_view">
    <xs:choice>  # I thought no standalone zone is permitted if 1 or more views
      <xs:attribute name="zone" minOccurs="0" maxOccurs="unbounded">
      <xs:attribute name="view" minOccurs="0" maxOccurs="unbounded">
    </xs:choice>
  <xs:complexType name="zone_or_view">
</xs:attributeGroup name="clause_zone_or_view">


<!-- BIND named.conf -->
<xs:complexType>
  <xs:choice>
    <xs:attribute name="clause_ACL" minOccurs="0" maxOccurs="unbounded">
    <xs:attribute name="clause_options" minOccurs="1" maxOccurs="1">
    <xs:attribute name="clause_statistics_channel" minOccurs="1" maxOccurs="1">
    <xs:attribute name="clause_logging" minOccurs="1" maxOccurs="1">
    <xs:attribute name="clause_masters" minOccurs="1" maxOccurs="unbounded">
    <xs:attribute name="clause_view_or_zone" minOccurs="1" maxOccurs="1">
    <xs:attribute name="clause_key" minOccurs="0" maxOccurs="unbounded">
    <xs:attribute name="clause_controls" minOccurs="1" maxOccurs="1">
    <xs:attribute name="clause_trusted_keys" minOccurs="0" maxOccurs="unbounded">
  </xs:choice>
</xs:complexType>