XOL meta model (cont’d)

<!ELEMENT ontology (name, (kb-type | db-type)?,

package?, version?, documentation?,

class*, slot*, individual*)>

<!ELEMENT name (#PCDATA)>

<!ELEMENT kb-type (#PCDATA)>

{…}

<!ELEMENT class (name, documentation?,

(subclass-of | instance-of | slot-values)*>

{…}

<!ELEMENT slot (name, documentation?,

(domain | slot-value-type |{…}| slot-values)*>

{…}

<!ELEMENT individual (name, documentation?,

(type | slot-values)*>

XML DTD for the meta model (Karp et al.)