<!ELEMENT environment (category+)>
<!ATTLIST environment
    name CDATA #REQUIRED>

<!ELEMENT category (element+)>
<!ATTLIST category
    name CDATA #REQUIRED>

<!ELEMENT element (property|element)*>
<!ATTLIST element
    name CDATA #REQUIRED>

<!ELEMENT property #PCDATA>
<!ATTLIST property
    name CDATA #REQUIRED>
