CFDI40115
El campo TipoCambio se debe registrar cuando el campo Moneda tiene un valor distinto de MXN y XXX.
In English TipoCambio (the exchange rate to pesos) is required when Moneda is anything but MXN or XXX.
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.