16/09/2026 (2.4.2): the Engineering Toolkit line now reads Free to run in the tool. The classes, the checks, the report and the exports are unchanged. The 9,590 scenarios in each tier and the 39 named checks were re-run on 2.4.2 with no findings; verified live after upload. 15/09/2026 (2.4.1): the emergency lighting note on the fire-survival circuit was read back against BS 5266-1:2025, which replaced the 2016 edition: supply cables to self-contained luminaires need not be fire-protected (8.1), and the wiring from a central power supply system should resist fire and retain circuit integrity (8.2.1), using one of the cables listed in 8.2.2. The smoke grade and flame class lines were revised in plain UK English. A new automated check reads every BS 5266-1 citation and the wording of every program file on both tabs, and fails on the 2.4.0 build; the 9,590 scenarios in each tier and the 39 named checks were re-run on 2.4.1 with no findings; no class, test or verdict changed; verified live after upload. 10/09/2026 (2.4.0): a check across every PD tool for a question asked of every user that only changed a badge or led to a redirect. Outdoors or underground the containment question was found to change only the badge, Compliant or Caution, while the substantive finding was the same either way, because the reaction-to-fire class outdoors is whatever the project specification states; the question is removed and the check prints that finding as one Caution line. On the Check a cable tab the corridor building type was found to lead, for a non-residential building, to a redirect rather than a result, since Approved Document B and BS 9999 set no cable class for wiring; the question is removed from that tab, the corridor is checked as the residential BS 9991 27.2.2 case and the non-residential position is stated as a line on every corridor result, with a corridor that is a protected escape route pointed to the BS 7671 422.2 location. The What do I need tab keeps both building types, where the requirement table differs. The enumeration was re-run on 2.4.0, 9,590 scenarios in each tier over the locations the tab now offers, with no findings; the automated tests gained checks that no building type and no outdoor containment question is asked on the check tab, that the corridor result shows the non-residential line and that an outdoor result is never Compliant on the class alone; the same tests fail on the 2.3.1 build. No class, test or clause changed; verified live after upload. 04/09/2026: the full input range was enumerated, 11,684 scenarios in each tier: every combination of flame, smoke, droplet and acidity grade, valid and invalid, against every location, building type, containment setting, specification preset and typed required class, plus every library cable against every location. Each verdict was compared with an independent reading of Regulation 422.2.1, its Note 1 and BS 9991 27.2.2, invalid codes were confirmed to receive no verdict, a better grade was confirmed never to receive a worse verdict, and a cable without a Declaration of Performance on file was confirmed to be asked for it. One finding: against a required class from a specification that asks for s2 or s3, a bare s1 printed Caution with the 422.2.1 transmittance note, where the EN 13501-6 scale places s1 above both. It was fixed in 2.3.1: in the class comparison a bare s1 reads Caution only against a required s1a or s1b, which state the light transmittance figure it lacks; the escape route locations under Regulation 422.2.1 are unchanged. The enumeration was re-run on 2.3.1 in both tiers with no findings, and the same tests fail on the 2.3.0 build. Verified live after upload. 03/09/2026 (2.3.0): every check line was audited against BS 7671:2018+A4:2026 Regulation 422.2.1 and its Note 1, read word for word. A bare s1 was found to be passed as meeting the 60% light transmittance the regulation names: s1 has no transmittance figure, the s1a and s1b grades do, so it now reads Caution and asks for the figure on the DoP. Acidity a1, which is the BS EN 60754-2 grade, was passed against the BS EN 60754-1 limit of 0.5%; it now reads Caution and asks for that figure. The fire-survival location said the CPR class still applied, where Note 1 places no CPR requirement on 560.8 fire-resisting cables; both tabs now state the Note 1 position. A common corridor was passed for any class run open; it now asks whether the cable is in metal conduit, trunking or tray and asks the building type, residential to BS 9991:2024 27.2.2 and other buildings to Approved Document B and BS 9999. A typed class is checked against the EN 13501-6 class format before any verdict, the verified source line prints only for the class the DoP declares, and the blank cable option clears the class box. The emailed and PDF report now include the findings table. The audit checks were run in both tiers; verified live after upload. 02/09/2026 (2.2.1): the revised wording was checked in the tool against the house style; no class, test or verdict changed. Every Euroclass in the tool is read from the manufacturer's own Declaration of Performance or a hosted datasheet, and each row links to that evidence: of 26 cables, 15 are verified from a Declaration of Performance, 5 have a manufacturer datasheet hosted with the tool, and 6 are marked DoP required because the maker publishes neither. Every one of those links is re-checked weekly and flagged when it stops resolving. The framing was verified against the sources in June 2026: UK law sets no minimum Euroclass for internal wiring (BS 7671 Appendix 2 Item 17, and Building Regulations regulation 7(3)(d) exempts electrical installations, while regulation 7(2) mandates a class only for external walls), so selection is by the BS 7671 component tests, flame propagation to BS EN 60332-1-2, smoke to BS EN 61034-2 and acid gas to BS EN 60754-1 added by A4:2026, with the Euroclass as the verification layer. Each specification preset states its own standards basis, BS 7671 422.2.1 for escape routes open and in containment and BS 9991 27.2.2 for surface wiring. No class in the library is inferred from a datasheet description or from a comparable product.