The Neuron DTD

  <!-- Neuron -->
  
  <!ELEMENT Neuron                (Data?,
                                   Axon*)>
  <!ATTLIST Neuron
          TYPEURI                  CDATA                  #REQUIRED>
  
  <!-- END Neuron -->
  
  
  <!-- Data -->
  
  <!ELEMENT Data                  (Tag*)>
  <!ELEMENT Tag                   (#PCDATA)>
  <!ATTLIST Tag
          NAME                     CDATA                  #REQUIRED>
  
  <!-- END Data -->
  
  
  
  <!-- Axon -->
  
  <!ELEMENT Axon                  (Data?)>
  <!ATTLIST Axon
          ID                       ID                     #REQUIRED
          ENDURI                   CDATA                  #REQUIRED
          TYPE                     CDATA                  #REQUIRED>
  
  
  <!-- END Axon -->