XV-PL-20
Zamowienie is for an advance invoice (ZAL) and its correction (KOR_ZAL), not for … (FA(3) information sheet, Zamowienie).
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
/fa:Faktura/fa:Fa
Test
$kind = ('ZAL', 'KOR_ZAL') or not(fa:Zamowienie)
Checked with KSeF FA(3)