If you need to validate an Ant build file with a validation engine that is different from the
built-in engine, you can configure external engines as custom Ant validation engines in the
Oxygen XML Editor preferences. After a custom validation engine is properly configured, it can be
applied on the current document by selecting it from the list of custom validation engines in
the 
Validation toolbar drop-down list. The document is validated against the
schema declared in the document.