CFDI40109

El TipoDeComprobante es T o P y el importe no es igual a 0, o cero con decimales.

In English In a transfer (T) or payment receipt (P), SubTotal must be 0.

error: the document is invalid

What the rule checks

As the rule set's publisher wrote it. The rule runs on every element the context matches, and fails where the test is false; the validator reports the line of that element.

Context
/cfdi:Comprobante
Test
not($type = ('T', 'P')) or mx:dec(@SubTotal) = 0

Checked with CFDI 4.0