R011 — Cross-Sheet Pattern Drift
Executive Summary
Key Takeaways
- ✓ R011 compares the same cell address across sheets that share the same structural classification, and flags a formula that deviates from the pattern the group otherwise shares.
- ✓ Sheets that cross-reference each other directly (a Revenue sheet feeding into a P&L sheet, for example) are functionally dependent, not structural copies of one another, and R011 suppresses the comparison entirely for that group rather than generating false positives.
- ✓ This is the cross-sheet counterpart to R004, which performs the equivalent comparison within a single row.
- ✓ A typical true trigger is the same projection row using a different formula on one period tab than on the others, from a copy-paste error or an undocumented exception.
Purpose¶
R011 detects a formula that deviates from the pattern shared by the same cell address across multiple sheets serving the same structural purpose — the cross-sheet counterpart to R004 (Formula Inconsistency), which performs the equivalent comparison within a single row on one sheet.
Detection Logic¶
Sheets are grouped by their structural classification (see Parsing & Workbook Ingestion), so only sheets serving a comparable role — a set of period tabs, for instance — are compared against one another. Before comparing, R011 checks whether any sheets within a classification group reference each other directly: if so, that group is functionally dependent (a Revenue sheet feeding a P&L sheet, both classified as Calculation sheets, is expected to have different formulas at the same address by design) and the entire group is excluded from comparison. For every remaining, non-excluded group, cells at the same address across the group's sheets are compared, and any cell whose formula deviates from the group's dominant pattern is flagged.
Why It Matters¶
Financial models built as a series of period tabs (Year 1, Year 2, Year 3, and so on) typically copy the same template forward across periods, with only the referenced cells shifting to the new period. A formula that silently diverges on one period's tab — often the result of a copy-paste error, or an undocumented one-off adjustment — is easy to miss in manual review, since each tab looks structurally identical at a glance and the deviation is buried inside the formula itself rather than visible in the model's layout.
Evidence Produced¶
A triggered R011 finding's evidence identifies the specific sheet and cell address of the deviating formula, its actual formula text, and a description stating how many of the group's sheets share the dominant pattern and what the deviating cell's formula contains instead.
Severity¶
High. Weight 7.0. R011 is not one of the five critical-override rules.
Example¶
Trigger. A financial model has separate Year 1 through Year 5 tabs, each a self-contained copy of the
same template with no cross-references between the tabs. Cell B12 on four of the five tabs reads
=B11*1.03; on the Year 3 tab it instead reads =B11*1.05. R011 flags the Year 3 tab's cell: it deviates
from the pattern the other four period tabs share.
Non-trigger — functional-tab suppression. A model has separate Revenue, P&L, and Cash Flow tabs, all
classified as Calculation sheets. Cell B12 differs across all three tabs, but the P&L tab's B12
formula references the Revenue tab, and the Cash Flow tab's B12 formula references the P&L tab. R011
detects this cross-referencing and suppresses the comparison for the entire group — the differing
formulas are expected, since the three tabs are functionally dependent rather than structural copies.
Recommended Remediation¶
Confirm whether the deviating cell's difference is intentional. If it is an error, correct the formula to match the group's dominant pattern. If it reflects a genuine, intentional exception for that specific period, document it so a future reviewer does not need to re-diagnose the same question.
Related Rules¶
R011 shares the Structural taxonomy category with the other Structural-category rules published in the Rule Reference, and is the cross-sheet counterpart to R004 — Formula Inconsistency — see the Rule Taxonomy page for the full category membership.
Related Articles¶
- Formula Consistency in Financial Models — the Knowledge Centre's buyer-facing technical guide to formula consistency across rows and periods.
Version History¶
No version-specific changes to R011'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 R011 check for?
The same cell address compared across multiple sheets that serve the same structural purpose — for example, Year 1, Year 2, and Year 3 tabs that are each a self-contained copy of the same template — flagging any sheet whose formula at that address deviates from the pattern the others share.
Why would sheets be excluded from this comparison?
If sheets in the same structural classification group reference each other directly — a Revenue sheet whose output feeds a P&L sheet, for instance — they are functionally dependent rather than structural copies of the same template, and comparing the same cell address across them would produce false positives, since the formulas are supposed to differ. R011 detects this cross-reference pattern and suppresses the comparison for that entire group.
How is R011 different from R004?
R004 compares cells within the same row of a single sheet against that row's own dominant pattern. R011 performs the equivalent comparison across multiple sheets, at the same cell address, among sheets serving the same structural role.
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.
R004 — Formula Inconsistency
R004 (Formula Inconsistency) flags a formula cell whose logic differs from the dominant pattern the rest of its row otherwise follows — an extra term, a different function, or a shifted reference. It is the general case of R001, catching a different formula rather than a typed constant, and deliberately excludes hardcoded cells from its own sample so the two rules never double-count the same cell. R004 is critical severity and one of five critical-override rules under the SM-2.0 scoring methodology.
Formula Consistency in Financial Models
Formula consistency in a financial model means that cells in the same row or column that perform the same calculation use identical or structurally equivalent formulas. In a time-series financial model, the formula in the Year 1 column of a revenue line should be structurally identical to the formula in the Year 5 column of the same line, with references shifting as appropriate across periods. A cell that contains a formula materially different from its neighbours in the same row is either performing a different calculation intentionally (which should be documented) or contains an error introduced by manual editing.