# Specification sources

wanderbooks' rules come from documents, not from anyone's memory. This
directory holds the authorities the engine's specs cite (`docs/spec/rules.md`
is the rule catalog), and every spec block in the code carries a `SOURCE:`
line pointing into it.

## The authority stack

There is no single "bible" of US bookkeeping. Authority is layered, and the
layers differ in what they cover and in whether we may copy them:

| Layer | What it governs | Copyright | Here |
|---|---|---|---|
| **Pacioli (1494), Geijsbeek translation (1914)** | The mechanics of double entry: debits equal credits, the trial balance, one money, writing only forward, correcting by opposite entry, closing into capital. No modern standard restates these; they predate every regulator. | Public domain | Vendored verbatim: `sources/pacioli-1494.md` |
| **IRS: Internal Revenue Code, Treasury Regulations, publications, form instructions** | Records and supporting documents, retention, accounting periods and methods, information returns (1099), capitalization (de minimis, 12-month rule), partners' capital, payroll taxes, rounding on returns | Public domain (17 U.S.C. §105; IRS.gov's content policy) | Vendored verbatim: `sources/irs-*.md`, `sources/us-public-domain-status.md` |
| **FASB Accounting Standards Codification (ASC)** | Authoritative US GAAP: cash flows (ASC 230), revenue and principal vs agent (ASC 606), foreign currency (ASC 830), credit losses and aging (ASC 326), property and depreciation (ASC 360) | © Financial Accounting Foundation | Cited by paragraph with short quotes only (in `rules.md`) |
| **FASB Concepts Statement No. 8, Chapter 4 (2021)** | Definitions of the five elements (it replaced Concepts Statement 6) | © Financial Accounting Foundation; non-authoritative | Cited with short quotes only |
| **Textbooks (OpenStax *Principles of Accounting, Vol. 1*)** | Conventions no standard states: normal balances, closing-entry mechanics, straight-line depreciation arithmetic | CC BY-NC-SA 4.0 (incompatible with this repo's license) | Cited with short quotes and attribution only |
| **Convention or decision** | Where no authority speaks: aging bucket edges, cent rounding among members, closed-period locks | — | Stated as CONVENTION or DECISION, with who decided and when |

## How to read a SOURCE line

```text
SOURCE: Pacioli ch. 36 (sources/pacioli-1494.md); IRS Pub. 583 (sources/irs-records.md)
SOURCE: ASC 830-20-30-1 (cited, rules.md B-3)
SOURCE: DECISION (Stephen, 2026-10-13)
SOURCE: CONVENTION (QuickBooks aging); nearest authority ASC 326-20-55-38 (illustrative)
```

A rule whose only source is CONVENTION or DECISION is a candidate for a
human to confirm or overturn; nothing else is.

## Vendoring rules

- Public-domain texts are copied **verbatim** (whitespace normalized), each
  with its URL, retrieval date, and the SHA-256 of the retrieved file, so
  anyone can check the excerpt against the original.
- Copyrighted sources are cited by paragraph, quoted briefly, never copied.
- When an authority changes (the IRS revises a publication; a statute is
  amended), add the new text beside the old with its effective date. Rules
  that depend on dates (1099 thresholds) must say which text applies when.

## Open: sources we could not verify

Read on 2026-10-13 through Deloitte's free DART roadmaps, which reproduce
ASC text: ASC 230-10-45-16 and -28, 326-20-55-37/38, 606-10-25-23, 45-2,
55-37/38, 830-20-30-1. Not yet verified (the ASC's free basic view needs a
login): ASC 360-10-35-4 (depreciation), 340-10 (prepaids), 230-10-45-10,
606-10-55-37B, 210 (balance sheet). Until someone with a FASB basic-view
account reads them, the rules that would cite them cite the textbook and
say so.