Rule at a Glance
| ID | Severity | Context (XPath) |
|---|---|---|
| Series ref. BR-44 | Fatal (error) | cac:AdditionalDocumentReference |
Schematron ID: ibr-052 | Field: cbc:ID (Supporting document reference, IBT-122) |
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Classification
Contextual — only invoices that attach supporting documentation (IBG-24) trigger this rule; a standard invoice with no attachments never encounters it.
What the Rule Is Checking
Wherever an cac:AdditionalDocumentReference block is present — used to attach or reference supporting documentation such as a delivery note, a purchase order copy, or a supporting calculation — it must include a non-empty cbc:ID identifying that document. The rule fails if the block exists (for example, carrying an embedded file) but the identifying reference is blank or missing.
Why This Rule Exists
A supporting document without an identifying reference is unusable to whoever receives it: there is no way to describe what the attachment is, cross-reference it against the transaction it supports, or retrieve it later during an audit trail review. The reference field is what turns a raw attachment into an identifiable, retrievable record tied to a specific business justification — a discount authorisation, a delivery confirmation, a contract clause.
UAE Data Example
PASSES ✓: cac:AdditionalDocumentReference includes <cbc:ID>DN-2026-04471</cbc:ID> identifying a delivery note attached to support the invoice.
FAILS ✗: An AdditionalDocumentReference block carries an embedded base64 attachment but the cbc:ID element is empty — often the result of an ERP attachment feature that auto-generates the binary payload but leaves the reference field for manual entry, which then gets skipped.
What Your ERP / IT Team Must Ensure
Require a document reference identifier as a mandatory field wherever your invoicing workflow allows attachments, not an optional label. Standardise a naming convention for these references (document type prefix plus sequence number) so they remain meaningful outside the ERP context. Test the attachment feature specifically for this field during UAT — attachment workflows are used inconsistently across departments and are a common source of overlooked validation gaps.
Related Rules
None directly dependent, though this rule is frequently exercised alongside allowance and charge reason references (IBT-097, IBT-104) where supporting justification documents are common.