Anything that wants to be sure that the data passed to it is structurally valid.

E.g.:

> All consumers are required to meet schema validation. Schema validation is the verification that the operations inside the SOAP Body match the contract created by Jack Henry in the XSD documents. It should be noted, that the VER_x tags are required in the requests to meet schema.

https://jackhenry.dev/jxchange-soap/getting-started/developm...

Ideally all of them.