R009 — Unresolved External Precedents
Executive Summary
Key Takeaways
- ✓ R009 flags a formula that references one or more external workbooks the audit could not resolve at the time it ran.
- ✓ It is distinct from R002 (Broken Links) in mechanism — R009 reads a formula's own recorded external precedents directly, rather than the parser's separately computed broken-links list.
- ✓ An unresolved external precedent does not necessarily mean the link is broken — it may mean the source workbook simply was not supplied alongside the model for this specific audit.
- ✓ One finding is produced per affected cell, with every unresolved external workbook name listed in the evidence.
Purpose¶
R009 detects formula cells that reference one or more external workbooks the audit could not resolve. This is a related but distinct concern from R002 (Broken Links): R009 reads each formula node's own recorded external precedents directly, rather than the separately computed broken-links list R002 consumes.
Detection Logic¶
Every formula node's recorded external precedents are checked. If any precedent is marked unresolved, the node is flagged, with every unresolved external workbook name it references listed together in a single finding for that cell.
Why It Matters¶
A formula that depends on an external workbook the audit could not access or confirm carries a distinct kind of risk from a fully internal formula: its correctness cannot be independently verified without also reviewing the linked source file. If that source workbook is genuinely no longer accessible, moved, or renamed, the formula's cached value may be stale without any visible indication. Even when the source workbook does exist but simply was not supplied for this audit, the dependency itself is worth surfacing — a reader relying on the audit's findings should know that a specific calculation's correctness rests on a file outside the one being reviewed.
Evidence Produced¶
A triggered R009 finding's evidence identifies the specific sheet and cell address of the affected formula, its formula text, and a description naming every unresolved external workbook the formula references.
Severity¶
High. Weight 7.5. R009 is not one of the five critical-override rules.
Example¶
Trigger. A formula reads =[Q3_Actuals.xlsx]Summary!$B$5, referencing an external workbook that was
not supplied alongside the model for this audit and could not be resolved. R009 flags the cell, naming
Q3_Actuals.xlsx as the unresolved external workbook.
Non-trigger. The same formula, but referencing an external workbook that was supplied and successfully resolved during the audit. R009 does not fire for this cell, regardless of whether R002 might separately flag a different, genuinely broken reference elsewhere in the model.
Recommended Remediation¶
Confirm the referenced external workbook is genuinely still the correct, current source, and supply it alongside the model for future audits so the dependency can be fully verified. Where the external dependency is no longer necessary or appropriate, replace the reference with an internally sourced value.
Related Rules¶
R009 shares the Structural taxonomy category with the other Structural-category rules published in the Rule Reference, and is closely related in concept to R002 — Broken Links — see the Rule Taxonomy page for the full category membership.
Related Articles¶
- Cross-Workbook Links — the Knowledge Centre's buyer-facing guide to the risks of multi-file model architectures.
Version History¶
No version-specific changes to R009's severity, weight, or category are recorded as of engine version 2.1.0. This section will be updated in the same edit as any future change to the rule's declared attributes.
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Frequently Asked Questions
What does FMAE rule R009 check for?
Formula cells that reference one or more external workbooks that could not be resolved when the audit ran — most commonly because the linked source file was not supplied alongside the model being audited.
How is R009 different from R002 (Broken Links)?
R002 reads a list of broken references the parser has already computed independently. R009 instead walks each formula node's own recorded external precedents directly, checking whether each one resolved. The two rules examine related but distinct facts about external references.
Does an unresolved external precedent always mean the link is broken?
Not necessarily. It may mean the source workbook genuinely no longer exists or has moved (the same condition R002 addresses), or it may simply mean the source workbook was not supplied alongside the model for this particular audit and could not be checked — R009's finding asks a reviewer to confirm the source workbook is accessible and correct.
Related Articles
FMAE Rule Taxonomy
Every rule in the FMAE structural rule pack declares a category attribute at the point it is defined in source — this is not a classification imposed on the rules afterward for documentation purposes, it is the classification the engine itself uses. Six categories cover all 26 rules — Structural (18 rules), Assumptions Governance (1), Integrity Controls (2), Structural Hygiene (1), Aggregation Logic (1), and Model Governance (3). This page publishes that taxonomy as the FMAE equivalent of a control catalog's classification scheme, cross-linked to the Rule Reference page for each member rule.
Finding Data Model & Confidence
Every FMAE finding carries the same fixed structure — which rule triggered it and that rule's identity at the time it ran, its evidence, a narrative explanation, and a confidence label of high, medium, or low. Confidence is a deterministic categorical label derived from how strongly a row's cells agree on a pattern, not a machine-learning probability estimate. Stating this plainly matters, since describing FMAE's confidence as AI-derived or probabilistic would overstate what the engine actually does.
R002 — Broken Links
R002 (Broken Links) flags a formula cell whose reference has broken — pointing at a deleted named range, a deleted worksheet, a reference-error cell, or an external workbook link the parser could not confirm resolves. It is critical severity and one of five critical-override rules under the SM-2.0 scoring methodology, meaning a single R002 finding caps the model's overall letter grade below A or B regardless of its numeric score.
Cross Workbook Links in Financial Models
Cross workbook links are formula references in one Excel workbook file that draw data from cells in a separate workbook file. When the source workbook is available and open, the link resolves dynamically. When the source workbook is closed or unavailable, Excel either updates the link by reading the file directly, or retains the last cached value without indicating that the displayed value may be stale. Cross workbook links introduce fragility through path dependency: any change to the name or location of the source file will break the link. In institutional financial models submitted for audit or lender review, cross workbook links that cannot be verified against available source files are a material structural finding.