+<!ENTITY % theorystructure
+ '(ht:AXIOM|ht:DEFINITION|ht:THEOREM|ht:VARIABLE|ht:SECTION|ht:MUTUAL)*'>
+
+<!ELEMENT ht:SECTION (%theorystructure;)>
+<!ATTLIST ht:SECTION
+ name CDATA #REQUIRED>
+
+<!ELEMENT ht:MUTUAL (ht:DEFINITION,ht:DEFINITION+)>
+
+<!-- Theory Items -->
+
+<!ELEMENT ht:AXIOM (Axiom)>
+<!ATTLIST ht:AXIOM
+ uri CDATA #REQUIRED
+ as (Axiom|Declaration) #REQUIRED>
+
+<!ELEMENT ht:DEFINITION (Definition|InductiveDefinition)>
+<!ATTLIST ht:DEFINITION
+ uri CDATA #REQUIRED
+ as (Definition|Inductive|CoInductive|Record) #REQUIRED>
+
+<!ELEMENT ht:THEOREM (type)>
+<!ATTLIST ht:THEOREM
+ uri CDATA #REQUIRED
+ as (Theorem|Lemma|Corollary|Fact|Remark) #REQUIRED>
+
+<!ELEMENT ht:VARIABLE (Variable)>
+<!ATTLIST ht:VARIABLE
+ uri CDATA #REQUIRED
+ as (Assumption|Hypothesis|LocalDefinition) #REQUIRED>
+
+
+
+
+
+
+
+
+