diff --git a/doc/xml/uml-1.4-umbrello.dtd b/doc/xml/uml-1.4-umbrello.dtd
index 735d1d063..f57eb6a83 100644
--- a/doc/xml/uml-1.4-umbrello.dtd
+++ b/doc/xml/uml-1.4-umbrello.dtd
@@ -1,71 +1,72 @@
 <?xml version="1.0" encoding="ISO-8859-1" ?>
 <!ENTITY % UmbrelloDiagrams SYSTEM "umbrello-diagrams.dtd" >
 %UmbrelloDiagrams;
 
 <!ENTITY % UmbrelloMisc SYSTEM "umbrello-misc.dtd" >
 %UmbrelloMisc;
 
 <!ELEMENT XMI.extensions (docsettings*, diagrams*, listview*, codegeneration*)>
 
 <!-- umbrello specific read only -->
 <!ENTITY % UML.EnumerationLiteral.umbrello '
     UML:EnumerationLiteral
 '>
 
 <!-- UML 1.4 and 2.x do not specify enumeration literal values -->
 <!ENTITY % UML.EnumerationLiteralAtts.umbrello '
     value CDATA #IMPLIED
 '>
 
 <!ENTITY % UML14 SYSTEM "01-02-16.dtd" >
 %UML14;
 
 <!-- ========= umbrello specific ========= -->
 <!ATTLIST UML:Operation
-   isOverride (true|false) #IMPLIED>
+   isOverride (true|false) #IMPLIED
+   isVirtual (true|false) #IMPLIED>
 
 <!ENTITY % UML.EntityAtts '
    isAbstract (true|false) #IMPLIED
    isLeaf (true|false) #IMPLIED
    isRoot (true|false) #IMPLIED
    isSpecification CDATA #IMPLIED
    name CDATA #IMPLIED
    namespace CDATA #IMPLIED
    visibility %UML.VisibilityKind; #IMPLIED
    xmi.id CDATA #IMPLIED'>
 
 
 <!ELEMENT UML:Entity (UML:EntityAttribute |
     UML:UniqueConstraint |
     UML:ForeignKeyConstraint)*>
 <!ATTLIST UML:Entity %UML.EntityAtts;>
 
 <!ELEMENT UML:EntityAttribute ANY>
 <!ATTLIST UML:EntityAttribute
    %UML.EntityAtts;
    allow_null CDATA #IMPLIED
    auto_increment CDATA #IMPLIED
    attributes CDATA #IMPLIED
    dbindex_type CDATA #IMPLIED
    initialValue CDATA #IMPLIED
    type CDATA #IMPLIED
    values CDATA #IMPLIED>
 
 <!ELEMENT AttributeMap ANY>
 <!ATTLIST AttributeMap
     key CDATA #IMPLIED
     value CDATA #IMPLIED>
 
 <!ELEMENT UML:UniqueConstraint (UML:EntityAttribute)>
 <!ELEMENT UML:ForeignKeyConstraint (AttributeMap)*>
 <!ATTLIST UML:ForeignKeyConstraint
    %UML.EntityAtts;
    comment CDATA #IMPLIED
    deleteAction CDATA #IMPLIED
    not CDATA #IMPLIED
    referencedEntity CDATA #IMPLIED
    updateAction CDATA #IMPLIED>
 
 <!ATTLIST UML:UniqueConstraint
    %UML.EntityAtts;
    isPrimary CDATA #IMPLIED>