The optional keyword VALIDATING is used to configure the service to use a validating or non-validating XML parser.

The default is to use a validating XML parser. This option can also be controlled by the service property 'validation.parser'.

A nonvalidating parser ensures that the XML data is well formed but does not verify that it is valid.

A validating parser uses the XML document defined DTD or XMLSchema grammars to validate that the XML data elements and attributes conform to the structural constraints of these schemas.

Why run in nonvalidating mode when a parser is capable of validation?

Because validation can significantly impact performance, especially when long and complex DTDs or XMLSchemas are involved.

Some developers find that while enabling validation during development and test phases is crucial, it's sometimes beneficial to suppress validation in production systems where document throughput is most valued, and the reliability of the data is already known.