Explain Spec

Interpret a CSI MasterFormat 2020 specification section in plain English, broken down by SectionFormat Part 1 (General) / Part 2 (Products) / Part 3 (Execution). Output is an inline explanation with verbatim §-citation. For a full spec audit (division completeness, drawing-spec coordination, reference-standard currency), use the spec-review skill instead.

Input you need

Before interpreting, gather:

• Spec section number and title — CSI MasterFormat 2020 format: XX YY ZZ — Title. Examples: 07 27 26 — Fluid-Applied Membrane Air Barriers, 08 11 13 — Hollow Metal Doors and Frames, 09 30 13 — Ceramic Tiling. Six digits with single spaces (no periods, no dashes between digit groups).
• Section text — the user must provide either:
  • A paste of the specific Part 1 / Part 2 / Part 3 article(s) the question is about (e.g., Part 2.04 Products — Acceptable Manufacturers), OR
  • The PDF path so arch-rag (for spec books indexed in the local RAG) or Read tool can pull the section.
  • Do not invent product names, manufacturer lists, reference standards, or installation requirements.
• Spec format — MasterSpec (AIA) / ARCAT / SpecLink+ / 4specs / project-custom. MasterSpec sections have specific Part 1 / Part 2 / Part 3 conventions; custom sections may not.
• Issue / phase — IFB (Issued for Bid) / 100% CD / IFC (Issued for Construction) / addendum / clarification. Affects whether contractors are bound by the language.
• AIA / contract context — AIA A201 §3.12.6 (Submittal review), AIA A201 §1.2.1 (Documents complement each other) — relevant for "if the spec says X but the drawing says Y" questions.
• Specific question — what the user wants to know. Examples: "Is this a basis-of-design or a substitution-allowed product?", "What's the warranty period for this finish?", "Is this single-source manufacturer language enforceable?", "What does 'comply with manufacturer's printed instructions' actually require?"

If any required input is missing, list the gap and stop. Do not interpret a spec section without seeing its actual text.

Output structure

Produce a single Markdown response in this layout:

# Explain Spec — [Section XX YY ZZ Title]

**Section:** [07 27 26 — Fluid-Applied Membrane Air Barriers]
**Spec format:** [MasterSpec / ARCAT / SpecLink+ / Custom]
**Issue:** [IFB / 100% CD / IFC / Addendum #X]
**Question:** [the user's specific question]

---

## Section role (in CSI MasterFormat 2020)

[1–2 sentences. Where this section sits in the MasterFormat hierarchy — division (e.g., Division 07 — Thermal & Moisture Protection), level 2 group (07 20 — Thermal Protection), level 3 (07 27 — Air Barriers). Why a project includes this section.]

## Part 1 — General

[2–4 sentences. Scope, references, submittals (per A201 §3.12), quality assurance, warranty. Quote the specific articles relevant to the user's question.]

> [verbatim quote of the relevant Part 1 article — e.g., 1.04.A.1]

— [Section XX YY ZZ §1.04.A.1]

## Part 2 — Products

[2–4 sentences. Basis-of-design (BOD), acceptable manufacturers, performance criteria, accessories. Distinguish "single-source" / "BOD-with-substitution" / "or-equal" / "open spec" — these have different procurement implications.]

> [verbatim quote of the relevant Part 2 article — e.g., 2.04.A]

— [Section XX YY ZZ §2.04.A]

## Part 3 — Execution

[2–4 sentences. Examination, preparation, installation, field QC, protection. Quote any "comply with manufacturer's instructions" or "as recommended by manufacturer" language — these create indirect submittal requirements.]

> [verbatim quote of the relevant Part 3 article — e.g., 3.05.B]

— [Section XX YY ZZ §3.05.B]

## Plain-English meaning

[3–5 sentences. What the section actually requires of the contractor, the architect, and the manufacturer. Distinguish prescriptive (specific product / brand / SKU) from performance (criteria the contractor's submittal must meet) language.]

## Coordination with the drawings

- [Bullet — drawings that reference this section (e.g., "Wall types W1, W2, W3 on A-101 reference §07 27 26"). Per AIA A201 §1.2.1, drawings and specs are complementary — flag any conflict the user should resolve via RFI.]
- [Bullet — adjacent specs this section depends on (e.g., "§07 27 26 references §07 21 00 for insulation that backs the air barrier").]

## Caveats

- This interpretation is based **only** on the spec text the user provided or that was retrieved verbatim. Cross-referenced articles, addenda, and reference standards (ASTM, ANSI, UL) that were not pulled may change the meaning.
- For binding interpretation on an `IFC` spec, the AOR's RFI response governs — not this command. Open an RFI via `draft-rfi` if the spec language is ambiguous.
- Single-source / sole-source language requires owner-approved sole-source justification on public projects (federal, GSA, USACE, state DGS, NYC SCA). Flag this if visible.
- [Bullet — reference-standard currency: e.g., "§1.03 cites ASTM E2178-13 — current edition is ASTM E2178-21. Verify with `spec-review` skill before bid."]

NA AEC conventions (enforce)

• English only. No Hangul anywhere.
• Imperial-first units (ft, in, sf, psf, °F, Btu, R-value); metric in parens only when useful. Use R-value for thermal performance, not metric U-values (W/m²K).
• CSI section numbers use MasterFormat 2020 convention: XX YY ZZ (six digits, single spaces, no periods, no dashes). Examples: 07 27 26, 08 11 13, 09 30 13. Never 07.27.26 or 7-27-26.
• Article numbers within a section use SectionFormat: 1.01, 1.04.A.1, 2.04, 3.05.B. Cite as §1.04.A.1 with the section preface (e.g., §07 27 26 §1.04.A.1).
• Reference standards name a NA standards body: ASTM, ANSI, UL, NFPA, ASHRAE, ICC-ES, AAMA, WDMA, SMACNA, SDI, NAAMM. Never BS, EN, JIS, or generic "the standard".
• Contract references — AIA A201 §1.2.1 (documents complement each other), AIA A201 §3.12 (Submittals), AIA B101 §3.4.5 (Architect's spec preparation), CSI MasterFormat 2020, CSI SectionFormat / PageFormat 2020.
• AHJs — name specifically (NYC DOB, FDNY, LADBS, DSA, CA HCAI, GSA, USACE, NYC SCA) when the question involves code-driven product requirements (e.g., NYC FDNY-listed materials, CA HCAI seismic anchorage). Never "the city" or "the AHJ" generically.
• Roles — Architect of Record (AOR), Engineer of Record (EOR), Owner, Owner's Representative, General Contractor (GC), Construction Manager (CM). Never "Director" as a project role.

Constraints

• Do not invent product names, manufacturer lists, model numbers, or reference standard editions. If the user did not paste the section text, route through arch-rag or Read tool first.
• Do not invent CSI section numbers. Cite only what appears in the user's input.
• Always quote verbatim from the spec for the article most relevant to the question — paraphrasing changes binding language.
• Distinguish prescriptive vs performance vs proprietary language clearly. These have different procurement and substitution implications under AIA A201 §3.4.2.
• This command coexists with the spec-review skill. If the user wants a full audit (Part 1/2/3 completeness, drawing-spec coordination, reference-standard currency, AHJ-specific references), redirect to spec-review rather than padding this command's output.
• Markdown only. This is an inline interpretation, not a transmittal document — no Word / PDF output and no aec-doc-gen dependency.

Workflow

1. Echo back what was parsed: section #, format, issue, question. One line.
2. If the section text is missing, list the gap and stop. Suggest arch-rag (indexed spec books) or Read tool as the retrieval path.
3. If the question implicates submittal review or substitution, surface the relevant AIA A201 §3.12 / §3.4.2 clause for the user's reference.
4. Produce the full Markdown response in one shot.
5. After the response, list any cross-referenced sections, addenda, or reference standards the user should pull next (e.g., "Section §07 21 00 (insulation) is referenced — pull that next via explain-spec if the air-barrier-to-insulation interface is the actual question").