# Specification Errata and Correction Log [`archive/four-js-specification.pdf`](archive/four-js-specification.pdf) (65 pages) contains internal defects, recorded here as E-1, E-2, and E-3. **All three are now resolved in [`SPECIFICATION.md`](SPECIFICATION.md)**, which was corrected by decision of the specification's author (2026-07-28) and is the working reference for this repository. The PDF is preserved unchanged as the original source and **still contains the defects** — use this file to translate between the two. --- ## E-1 — `Part VII` was used for two different parts — ✅ RESOLVED The PDF contains two distinct parts both labelled `Part VII`: | Occurrence | Heading | Covers (PDF numbering) | | ---------- | --------------------------------------------------------------------------------- | --------------------------------------------------------------------------------- | | First | `Part VII - Complete Graphics, Rendering, Application, and Platform Architecture` | §45 _Application Model_ → §67 _Clipping, Masks, and Stencils_ (continuing to §97) | | Second | `Part VII - Package Architecture` | §45 _Proposed Monorepo_ → §49 _Solver Packages_ | **Resolution applied in `SPECIFICATION.md`:** the second occurrence became a new `Part VIII - Package Architecture`, and every later part shifted by one: | PDF | SPECIFICATION.md | | ------------------------------------------------------------------------------- | -------------------- | | Part VII - Complete Graphics, Rendering, Application, and Platform Architecture | Part VII (unchanged) | | Part VII - Package Architecture | **Part VIII** | | Part VIII - Implementation Plan | **Part IX** | | Part IX - Public API Examples | **Part X** | | Part X - Flagship Demonstrations | **Part XI** | | Part XI - Revised MVP | **Part XII** | | Part XII - Final Design Statement | **Part XIII** | ## E-2 — Section numbers 45–67 were assigned twice — ✅ RESOLVED In the PDF, the second `Part VII` restarts section numbering at 45, so the range 45–67 is used twice and bare references like "§49" are ambiguous. **Resolution applied in `SPECIFICATION.md`:** the first range (§1–97) is unchanged; the second range was renumbered by **+53** to §98–120, giving a single sequence 1–120. Map for the renumbered sections: | PDF § | SPECIFICATION.md § | Title | | ----- | ------------------ | ---------------------------------------------- | | 45 | 98 | Proposed Monorepo | | 46 | 99 | Motion Package | | 47 | 100 | Animation Package | | 48 | 101 | Physics Package | | 49 | 102 | Solver Packages | | 50 | 103 | Phase 0 - Project Foundation | | 51 | 104 | Phase 1 - Math, Scene, and Time | | 52 | 105 | Phase 2 - Motion Foundation | | 53 | 106 | Phase 3 - Renderer Foundation | | 54 | 107 | Phase 4 - Animation Core | | 55 | 108 | Phase 5 - Physics API and First Solver Adapter | | 56 | 109 | Phase 6 - Joints and Constraints | | 57 | 110 | Phase 7 - Physics-Animation Integration | | 58 | 111 | Phase 8 - Advanced Motion | | 59 | 112 | Phase 9 - Particles and GPU Motion | | 60 | 113 | Phase 10 - Replay, Snapshots, and Diagnostics | | 61 | 114 | Basic Animated Object | | 62 | 115 | Dynamic Physics Object | | 63 | 116 | Motorized Hinge | | 64 | 117 | Physics and Animation Blend | | 65 | 118 | "One Scene, Everything Moves" | | 66 | 119 | Engineering Demonstration | | 67 | 120 | MVP Requirements | Citation convention: plain section references (e.g. "§102") now mean `SPECIFICATION.md` numbering. When citing the PDF, say so explicitly (e.g. "PDF §49, second range"). ## E-3 — Solver packages contradiction — ✅ RESOLVED The PDF's _Solver Packages_ section (PDF §49, second range) named four solver adapter packages (`physics-rapier`, `physics-box2d`, `physics-matter`, `physics-cannon`), while the _Proposed Monorepo_ tree (PDF §45, second range) listed only `physics-rapier`, `physics-box2d`, and `physics-soft` (a soft-body package, not a solver adapter). A full cross-check of every `@fourjs/` reference found no other mismatches. **Resolution (owner decision, previously recorded here and now applied to the text):** the monorepo tree wins. §102 (Solver Packages) in `SPECIFICATION.md` now lists only `@fourjs/physics-rapier` and `@fourjs/physics-box2d`, with a note that Matter.js and Cannon-es (potential adapters per §37) may be added by future amendment. The scaffold contains `physics-rapier`, `physics-box2d`, and `physics-soft` only; `physics-matter` and `physics-cannon` must not be added without a further amendment. ## Extraction artifacts — ✅ REPAIRED `SPECIFICATION.md` originally carried PDF text-extraction noise, all repaired in the corrected rendering: kerning splits (`AScene`, `A void`, `A VIF`, `W orker-rendering`, `T ests`, `Digital T win`, `T ooling`), the `efficient` ligature, mid-word line-break hyphens (e.g. `appli-`/`cation`), and the wrapped subtitle. Two line-end hyphens were genuine compounds and were preserved: `human-readable`, `vector-level`. The corrected rendering also adds Markdown headings (`##` parts, `###` sections); no normative wording was changed other than the E-3 resolution described above. --- ## Scope note: revisions vs. errata This file covers only the PDF's extraction/numbering defects and their resolution. Substantive amendments to the specification (revision 1.1 applying `SPEC-REVIEW.md` R-1–R-35, revision 1.2 confirming the §86 payload budget) are recorded in the **amendments table at the top of `SPECIFICATION.md`**, not here. The archived PDF is **frozen at the pre-1.0 text**: it predates all revisions in addition to carrying the defects above. ## Non-defects (checked and dismissed) Recorded so they are not "rediscovered" later: - **Section 65 (PDF second range; now §118) is not missing.** Its title begins with a typographic quote (`"One Scene, Everything Moves"`), which heading scans can miss. - **Repeated low numbers (1., 2., 3., …) scattered through the text are numbered _lists_,** not sections — e.g. the four fundamentals in §1 _Vision_. Only the PDF's 45–67 range was a genuine collision.