FX-SCH-A-000028
Element 'ram:BuyerTradeParty' must occur exactly 1 times.
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.
Factur-X MINIMUM rules 1.09
Factur-X BASIC WL rules 1.09
Factur-X BASIC rules 1.09
Factur-X EN 16931 rules 1.09.2
Factur-X EXTENDED rules 1.09.2
Context
/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement
Test
count(ram:BuyerTradeParty)=1
Checked with Factur-X / ZUGFeRD MINIMUM