DC510
Foreign source currency does not match document currency: TaxExchangeRate's SourceCurrencyCode is …, the document currency ….
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
/*Test
not($rate) or normalize-space($rate/cbc:SourceCurrencyCode) = $currencyChecked with MyInvois e-Invoice