@Override
    public DatatypeBuilder createDatatypeBuilder(String baseTypeLocalName)
            throws DatatypeException {
        return new ParameterlessDatatypeBuilder(createDatatype(baseTypeLocalName));
    }
Returns a <code>DatatypeBuilder</code> for a named datatype. This method is 
unnecessary for direct access. Just use <code>createDatatype</code>.
@param baseTypeLocalName the local name
@return a <code>ParameterlessDatatypeBuilder</code> for the local name
@see org.relaxng.datatype.DatatypeLibrary#createDatatypeBuilder(java.lang.String)
src/nu/validator/datatype/Html5DatatypeLibrary.java