ENTITYDatatypeValidator implements the DatattypeValidator interface.
IDDatatypeValidator - ID represents the ID attribute type from XML 1.0 Recommendation.
IDREFDatatypeValidator - represents the IDREFS attribute type from XML 1.0 recommendation.
StringValidator validates that XML content is a W3C string type.
The string datatype represents character strings in XML.
IDDatatypeValidator - ID represents the ID attribute type from XML 1.1 Recommendation.
IDREFDatatypeValidator - represents the IDREFS attribute type from XML 1.1 recommendation.