XSD validation is necessary, but not sufficient.

XSD checks XML structure, element order and data types. It cannot by itself establish that references resolve, mappings are known, declared totals reconcile or transactions balance.

What XSD catches

• Missing required elements and incorrect ordering.
• Invalid dates, numbers and text formats.
• Values outside schema-defined constraints.

What requires semantic checks

• References to absent accounts or counterparties.
• Unknown tax or account-grouping mappings.
• Declared totals that differ from transaction lines.
• Unbalanced transactions and inconsistent selection periods.