Customization Form DTD

<?xml version="1.0"?>

<!DOCTYPE cf [
     <!ELEMENT cf (directive?, resource*, element*, id*, group*)>

     <!ELEMENT group (directive?, resource*, element*, id*, group* )>
     <!ELEMENT element (directive?, resource*, id*)>
     <!ELEMENT id (directive?, resource*)>

     <!ELEMENT resource (data|file|url)>
     <!ELEMENT directive (data)>

         <!ELEMENT data (#PCDATA)>
         <!ELEMENT file (#PCDATA)>
         <!ELEMENT url (#PCDATA)>

         <!ATTLIST resource
                 name CDATA #REQUIRED
                 type CDATA #REQUIRED>
         <!ATTLIST group
                 name CDATA #REQUIRED>
         <!ATTLIST element
                 name CDATA #REQUIRED>
         <!ATTLIST id
                 name CDATA #REQUIRED>
]>