This element serves as the head of a substitution group
for extensibility elements that wish to appear as a child
of wsdl:message and/or wsdl:interface
Abstract Element msgAndinterfaceExt
The msgAndinterfaceExt element cannot have "xsi:nil" as an attribute.
The msgAndinterfaceExt element in XML instance can be substituted with other elements.
<xs:documentation>
This element serves as the head of a substitution group
for extensibility elements that wish to appear as a child
of wsdl:message and/or wsdl:interface
</xs:documentation>