Primary sources
NIST Revised Unit Conversion Factors and Handbook 133 Appendix E support exact inch, foot and area conversions. OSHA Residential Fall Protection and HSE Roof work/HSG33 support the safety boundary. Google Search Central and publisher policies guide public presentation.
Source records include owner, title, URL, access date, supported claim, content type, rights note and review cadence. Manufacturer coverage is visitor-entered unless permission and provenance are documented.
Corrections
Report a suspected factual, formula, accessibility or legal issue through the Maple Web Group contact page and identify RoofFigured, the page, the observed result and the inputs needed to reproduce it.
Material formula corrections trigger new fixtures, independent cross-checks, a calculation-version change and a visible change-log entry. Editorial wording corrections retain their review date.
Published source register
| Owner and title | Claim supported | Reviewed | Category / use | Cadence |
|---|---|---|---|---|
| NIST — Revised Unit Conversion Factors | Exact international inch and foot relationship to the metre | 4 Sep 2026 | Primary government metrology; factual reference | Annual |
| NIST — 2026 Handbook 133 Appendix E | Unit names and length/area conversion cross-check | 4 Sep 2026 | Official handbook; facts independently presented | New edition |
| OSHA — Residential Fall Protection | US roof-work safety boundary | 4 Sep 2026 | Official safety guidance; linked, not reproduced | Six-monthly |
| HSE — Roof work | UK roof-work safety boundary | 4 Sep 2026 | Official safety guidance; linked, not reproduced | Six-monthly |
| Google Search Central — Canonicals | Canonical URL implementation | 4 Sep 2026 | Official technical guidance; implementation reference | Annual |
Correction history
4 September 2026: corrected the staging prototype’s label-only unit treatment, missing canonical metadata, workbench subtotal visibility and favicon set. No underlying trigonometric formula defect was identified. Future factual or formula corrections will state the affected calculation, reason, added regression test and release version here.