Exactly one product end user URI ID

Error FX-SCH-A-000727 Factur-X

Element 'ram:URIID' must occur exactly 1 times.

Mandatory rule: As long as it is violated, the invoice is invalid and will be rejected by validators.
What is wrong

ram:URIUniversalCommunication does not contain exactly one ram:URIID element. The URI ID is either missing or occurs more than once.

What the rule means

The URI ID contains the product end user's electronic communication address. Requiring exactly one element ensures that this information is unambiguous.

Please provide exactly one URI ID for the product end user

The product end user's electronic communication details are missing ram:URIID, or the element occurs more than once. Having exactly one such element makes the entry unambiguous.

What to do
  1. Locate ram:URIUniversalCommunication for the product end user.
  2. Check the ram:URIID elements it contains.
  3. Ensure that exactly one ram:URIID element is present.
  4. Generate the invoice again and validate it.
What it looks like
✗ Triggers the message 
<ram:URIUniversalCommunication>
  <ram:URIID>urn:example:one</ram:URIID>
  <ram:URIID>urn:example:two</ram:URIID>
</ram:URIUniversalCommunication>
✓ Correct 
<ram:URIUniversalCommunication>
  <ram:URIID>urn:example:one</ram:URIID>
</ram:URIUniversalCommunication>
Technical details

The rule counts the direct ram:URIID elements in ram:URIUniversalCommunication and requires the count to be 1.

Where the rule applies

The rule applies to ram:URIID in the product end user's electronic communication details.

Context (rule/@context)
/rsm:CrossIndustryInvoice/rsm:SupplyChainTradeTransaction/ram:ApplicableHeaderTradeAgreement/ ram:ProductEndUserTradeParty/ram:URIUniversalCommunication
Test expression (assert/@test)
count(ram:URIID)=1