Simple type definitions define a simple datatype and specify the constraints
and information about the values of attributes or text-only elements.
The <simpleType> element contains attributes, which are described by
XML Schema Part 1: Structures of the standard.
Simple type definitions come in three varieties:
The XML Schema model java interface for a <simpleType> is
org.eclipse.xsd.XSDSimpleTypeDefinition and
can be created by calling
org.eclipse.xsd.XSDFactory.eINSTANCE.createXSDSimpleTypeDefinition().
