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Evidence
Karthik P edited this page Nov 1, 2026
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This page is the claims register: for every factual claim the wiki and the research documents make, it gives the source or reproducible check, the verbatim text or check ID, how it was checked, and the result.
Last reviewed: 1 Nov 2026
How this page is made. The page is generated by research/evidence/render_evidence.py from the register research/evidence/claims.json in the repository, so edit the register, not this page. research/evidence/check_quotes.py fetches every source that has a quote and confirms that the quote still appears in it. The Verified column gives the date of the last successful check. The register holds 86 claims: 56 verified, 18 quote corrected, 8 fetch failed, 4 unverified.
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Method. Fetched page: the source page (or API response) was downloaded and the quote compared with its text after removing markup and collapsing whitespace. Script check: reproduced by
research/verification/verify_claims.py, standard-library Python, rerun by CI; the ID is the check name. Filing: an SEC filing. Secondary: a source that is not the authority for the fact (Wikipedia, a forum post, an archived copy, or a summarised fetch). - Status. Verified: the quote or value matches. Quote corrected: the source exists but the research documents' wording was not verbatim or overstated it; the corrected wording is given. Fetch failed: the script could not fetch the source (it never requests sec.gov); the row says how it was checked instead. Unverified: no authoritative source found; treat as an open question.
- The two research documents (the design proposal and the gap analysis) are not published; where a row says "proposal" or "gap analysis", it names the document that made the claim.
| Claim | Source | Verbatim quote or check | Method | Status | Verified |
|---|---|---|---|---|---|
| A 52-53-week tax year ends on the weekday that last occurs in a month, or the one nearest the month's last day | IRS Publication 538 | "Whatever date this same day of the week last occurs in a calendar month, or Whatever date this same day of the week falls that is nearest to the last day of the calendar month." | Fetched page | Verified | 1 Nov 2026 |
| NRF fiscal 2006, 2012, 2017 and 2023 have 53 weeks | NRF | "2006, 2012, 2017 and 2023 are all 53-week years." | Fetched page (also cited vector nrf-53-week-years.json) |
Verified | 1 Nov 2026 |
| NRF restates a 53-week year by shifting each week back one week | NRF | "pushing each week of the 53-week year back one week, thereby ignoring the first week of the fiscal year". The research documents cut the sentence after "the first week". | Fetched page | Quote corrected (completed) | 1 Nov 2026 |
| Broadcast months end on the last Sunday | Wikipedia | "on the last Sunday of the month", within "with the period ending on the last Sunday of the month" | Secondary | Verified | 1 Nov 2026 |
| Broadcast weeks run Monday to Sunday; months end on the last Sunday | TVB | "The standard broadcast week starts on Monday and ends on Sunday. The standard broadcast month ends on the last Sunday of the calendar month." | Fetched page | Verified | 1 Nov 2026 |
| Iran's calendar is "not determined by a mathematical formula" | Wikipedia | "This calendar is not determined by a mathematical formula". The sentence is about leap years. | Secondary | Verified (secondary source) | 1 Nov 2026 |
| The US federal fiscal year runs 1 October to 30 September | 31 U.S.C. 1102 (LII) | "The fiscal year of the Treasury begins on October 1 of each year and ends on September 30 of the following year." | Fetched page | Verified | 1 Nov 2026 |
| Japanese local governments publish by era year (令和8年度) | Sakura City | 令和8年度 appears on the page. The mapping to April 2026 to March 2027 needs a second source. | Fetched page | Verified (for the label; the mapping is unverified) | 1 Nov 2026 |
sec.gov refuses automated requests whose User-Agent does not give a contact email address, and the project's scripts send none. check_quotes.py therefore does not fetch sec.gov and reports these rows as fetch failed. The quotes were checked in excerpts returned by a summarising web fetch, which is not a character-for-character comparison. Apple was compared character for character against a saved copy of the filing.
| Claim | Source | Verbatim quote or check | Method | Status | Verified |
|---|---|---|---|---|---|
| Apple's fiscal year ends on the last Saturday of September; fiscal 2023 had 53 weeks and a 14-week first quarter | Apple 10-Q, quarter ended 30 Dec 2023 | "the 52- or 53-week period that ends on the last Saturday of September"; full quotes in apple-10q-2023-12-30.json
|
Filing (saved copy, character comparison) | Verified | 31 Oct 2026 |
| Vishay: 13-week periods, except Q1 always begins on 1 January and Q4 always ends on 31 December | Vishay 10-Q (2024) | "13-week periods beginning on a Sunday and ending on a Saturday, except for the first fiscal quarter, which always begins on January 1, and the fourth fiscal quarter, which always ends on December 31" | Filing (summarised excerpt) | Fetch failed (matched in excerpt) | 31 Oct 2026 |
| Vishay's reported Q1 ends (1 Apr 2023, 30 Mar 2024) match "Saturday nearest 31 March" | Vishay 10-Q (2024) | The Q1 anchor is not named in the filing and stays illustrative | Filing (summarised excerpt) | Fetch failed (anchor illustrative) | 31 Oct 2026 |
| Costco uses thirteen four-week periods | Costco 10-K (fiscal 2017) | "thirteen, four-week periods" | Filing (summarised excerpt) | Fetch failed (matched in excerpt) | 31 Oct 2026 |
| Kroger uses thirteen 28-day periods | Kroger 10-K (fiscal 2018) | "thirteen 28-day periods" | Filing (summarised excerpt) | Fetch failed (matched in excerpt) | 31 Oct 2026 |
| Care.com's year-end rule | Care.com 10-Q (fiscal 2019 Q2) | "the Saturday in December closest and prior to December 31" | Filing (summarised excerpt) | Fetch failed (matched in excerpt) | 31 Oct 2026 |
| Care.com's quarter-end rule | Care.com 10-Q (fiscal 2019 Q2) | "on the Saturday that falls closest to the last day of the third month" | Filing (summarised excerpt) | Fetch failed (matched in excerpt) | 31 Oct 2026 |
| Care.com changed to a calendar year during fiscal 2019, so the C16 divergence describes the two rules as written, not its current calendar | Care.com 10-Q (fiscal 2019 Q2) | "from a 52 or 53 week fiscal year to a calendar year" | Filing (summarised excerpt) | Fetch failed (matched in excerpt) | 31 Oct 2026 |
| SEC frames can mix facts with different reporting periods | SEC API documentation | "different reporting start and end dates" | Secondary (summarising web fetch) | Fetch failed (matched in excerpt) | 31 Oct 2026 |
| Claim | Source | Verbatim quote or check | Method | Status | Verified |
|---|---|---|---|---|---|
| SAP special periods subdivide the last posting period | SAP Learning | "Special periods are used to subdivide the last posting period for closing operations." The gap analysis quoted "subdivide the last posting period for closing work", which is not verbatim. | Fetched page | Quote corrected | 1 Nov 2026 |
| SAP supports year-specific week-based variants | SAP Learning | Week-based Fiscal Year Variant ("4-4-5" fiscal year variant) for the fiscal year 2024. The gap analysis's "4-4-5 for fiscal year 2024" is not verbatim. | Fetched page | Quote corrected | 1 Nov 2026 |
| 226 Indian listed companies did not follow a March year end | Business Standard, Wayback copy | "as many as 226 listed companies don't follow financial years ending March". The article does not say the Companies Act, 2013 "moved" them; it describes a tribunal exemption. | Secondary (archived copy of the article) | Quote corrected | 1 Nov 2026 |
| Thomas Cook (India) could have a 15-month year | Business Standard, Wayback copy | "it could have a 15-month period from January 2015 to March 2016". Conditional, and called a period, not a year. | Secondary (archived copy) | Quote corrected | 1 Nov 2026 |
| India: FY 2025-26 and AY 2026-27 are two names for one year | Income Tax Department FAQ | They are different years: AY 2026-27 is the year after FY 2025-26, in which its income is assessed. From 1 April 2026 the Income-tax Act, 2025 uses "tax year", and "the use of term 'assessment year' has been discontinued". | Fetched page | Quote corrected (claim corrected) | 1 Nov 2026 |
| Claim | Source | Verbatim quote or check | Method | Status | Verified |
|---|---|---|---|---|---|
| fiscalyear's latest release is 0.4.0 of 17 Feb 2022 | PyPI JSON |
info.version = 0.4.0; upload time 2022-02-17T03:18:26
|
Fetched page (API) | Verified (as of 31 Oct 2026) | 1 Nov 2026 |
| fiscalyear has about 345,000 downloads a month | ecosyste.ms | 339,074 last month (snapshot synced 25 Aug 2026), not about 345,000 | Fetched page (API) | Quote corrected (figure replaced by the source's value) | 31 Oct 2026 |
| fiscalyear has about 345,000 downloads a month | pypistats | 206,407 last month as of 31 Oct 2026, not about 345,000 | Fetched page (API) | Quote corrected (figure replaced by the source's value) | 31 Oct 2026 |
| fiscalyear issue #1 (4-4-5 support) is open since May 2017 | Issue #1 | Title "Support for a 4-4-5 calendar", open, created 2017-05-27 | Fetched page (GitHub API) | Verified | 1 Nov 2026 |
| Issue #6 asks for several calendars in one app | Issue #6 | "Make it possible to use multiple calendar settings in the same app.", open | Fetched page (GitHub API) | Verified | 1 Nov 2026 |
| Issue #10 asks for week numbers and has 20 comments | Issue #10 | "Support for week number of a date in a FiscalYear", open, 20 comments | Fetched page (GitHub API) | Verified | 1 Nov 2026 |
| Issue #20 asks for a 29 February month end | Issue #20 | "Support February 29 month end date for leap year", open | Fetched page (GitHub API) | Verified | 1 Nov 2026 |
| fiscalyear v0.2.0 fixed a crash for calendars starting at the end of a month | Release v0.2.0 | "Corner case where fiscal calendar starting at the end of the month could crash is fixed (#8)" | Fetched page | Verified | 1 Nov 2026 |
| pandas FY5253 supports "nearest" and "last", and chooses the quarter with the extra week | pandas FY5253Quarter |
variation "nearest" or "last"; qtr_with_extra_week
|
Fetched page | Verified | 1 Nov 2026 |
| fiscal_calendar is one 4-5-4 pattern | PyPI JSON | Description: "structured based on the 4-5-4 week schema and the 4-5-5 week schema"; requires pandas, numpy and reportlab | Fetched page (API) | Quote corrected | 1 Nov 2026 |
retailcalendar is NRF 4-5-4 with US and Brazil holidays, GPL-3.0 |
PyPI JSON | Classifier "GNU General Public License v3 (GPLv3)"; description names public holiday calendars for Brazil and the United States | Fetched page (API) | Verified | 1 Nov 2026 |
retail-calendar's restated option is deprecated |
npm registry | README heading "restated [Removed]" and "This is no longer supported. All 53 week calendars are not restated". No version has an npm deprecated field. |
Fetched page (API) | Quote corrected ("[Removed]", not deprecated) | 1 Nov 2026 |
| retail-calendar drops the 53rd week with month -1 by default | npm registry | "LAST week of year is "dropped" for 53-week years."; the README calls this the default, and its example shows monthOfYear // -1
|
Fetched page (API) | Verified | 1 Nov 2026 |
| retail-calendar has about 870 weekly downloads | npm downloads API | 5,252 downloads for 2026-10-23 to 2026-10-29; latest version 4.1.2 of 30 Oct 2024 | Fetched page (API) | Quote corrected (5,252 as of 31 Oct 2026) | 31 Oct 2026 |
| fiscal-year-calendar is at v3.2.1 | npm registry |
dist-tags.latest = 3.2.1, published 2025-07-30 |
Fetched page (API) | Verified (as of 31 Oct 2026) | 1 Nov 2026 |
| ThreeTen-Extra has about 8,064 configurations | AccountingChronologyBuilder Javadoc | "There are approximately 7 x 2 x 12 x 4 x 12/13 x 2 = 8064 combinations." The product as written is 16,128 (with 12) or 17,472 (with 13), so "= 8064" does not match its own arithmetic. | Fetched page | Quote corrected (source internally inconsistent) | 1 Nov 2026 |
| Fiscal5253 offers fiscal, restated and truncated views | MetaCPAN | "The legal values are "fiscal", "restated", and "truncated" when the style is being set." | Fetched page (through the metacpan API, because the main site showed a client challenge) | Verified | 1 Nov 2026 |
| Tempo lists sprints, pay periods and academic terms as unsupported | Tempo documentation | "What is not here yet" lists "Sprints and pay periods" and "Irregular academic terms". Academic years are supported. | Fetched page | Quote corrected | 1 Nov 2026 |
| Power BI handles retail, 13-month and lunar calendars | Power BI blog, Wayback copy | "Gregorian, shifted Gregorian, retail (445, 454, 544), 13-month, lunar, and more". Post dated 22 Sep 2025; a Preview feature. The original URL returned 403. | Secondary (archived copy) | Verified (in archived copy) | 1 Nov 2026 |
| dbt-date builds a 4-5-4 fiscal period table | dbt-date README |
get_fiscal_periods(dates, year_end_month, week_start_day, shift_year=1); the README also says "This package is no longer actively supported." |
Fetched page | Verified | 1 Nov 2026 |
| A crates.io search for "fiscal" returns 109 crates, mostly Brazilian and Italian | crates.io API |
meta.total = 109 as of 31 Oct 2026. By description 22 are Brazilian and 3 Italian, so "mostly" is wrong. No description mentions a 52/53-week or 4-4-5 engine. |
Fetched page (API) | Quote corrected | 31 Oct 2026 |
The fiscal crate is a Brazilian NF-e library |
crates.io API | Description "Brazilian fiscal document library (NF-e/NFC-e)"; version 0.8.1 | Fetched page (API) | Verified (as of 31 Oct 2026) | 1 Nov 2026 |
fiscal-rs is reserved |
crates.io API | "Reserved crate name for future Fiscal related work in Rust" | Fetched page (API) | Verified | 1 Nov 2026 |
The name fiscalclock was free on crates.io, PyPI and npm before the first release |
The registry APIs at crates.io/api/v1/crates/fiscalclock, pypi.org/pypi/fiscalclock/json and registry.npmjs.org/fiscalclock
|
All three returned "not found" on 31 Oct 2026, before 0.1.0 was published. The name is now taken by fiscalclock itself (rows below). | Fetched page (API) | Verified (before publication on 31 Oct 2026) | 31 Oct 2026 |
| fiscalclock 0.1.0 is published | crates.io API |
max_version = 0.1.0; crate created 2026-10-31T18:10:25Z |
Fetched page (API) | Verified (as of 1 Nov 2026) | 1 Nov 2026 |
| fiscalclock 0.1.0 is published | PyPI JSON |
info.version = 0.1.0; first file uploaded 2026-10-31T18:10:34 |
Fetched page (API) | Verified (as of 1 Nov 2026) | 1 Nov 2026 |
| fiscalclock 0.1.0 is published | npm registry |
dist-tags.latest = 0.1.0; package created 2026-10-31T18:19:27Z |
Fetched page (API) | Verified (as of 1 Nov 2026) | 1 Nov 2026 |
| Claim | Source | Verbatim quote or check | Method | Status | Verified |
|---|---|---|---|---|---|
abi3 wheels do not load on free-threaded Python before 3.15; abi3t arrives in 3.15 |
PEP 803 | "The Stable ABI is currently not available for free-threaded builds." Header: Status Final, Python-Version 3.15, Resolution 30-Mar-2026 | Fetched page | Verified | 1 Nov 2026 |
| Polars' Arrow interface needs no pyarrow | Polars user guide | "No required dependency on pyarrow." (capital N, in a list for library maintainers). The page does not name DuckDB or pandas. | Fetched page | Quote corrected | 1 Nov 2026 |
| Jiff has "no timeline" for 1.0 | Jiff README | "I don't currently have a timeline for a Jiff 1.0 release." "no timeline" is a paraphrase, not a quote. Latest jiff on crates.io is 0.2.38 as of 31 Oct 2026. | Fetched page | Quote corrected | 1 Nov 2026 |
| wasm-bindgen moved to a new organisation | Rust blog, 21 Jul 2025 | "The wasm-bindgen repository is going to be transferred to a new wasm-bindgen organization with new additional maintainers." | Fetched page | Verified | 1 Nov 2026 |
The rustwasm organisation was archived in September 2025 |
rustwasm on GitHub |
GitHub API archived_at is 2025-08-25, not September 2025. wasm-pack now lives at wasm-bindgen/wasm-pack and is not archived. |
Fetched page (GitHub API) | Quote corrected (25 Aug 2025) | 1 Nov 2026 |
| NAPI-RS v3 was released in July 2025 | NAPI-RS blog | "NAPI-RS v3 - WebAssembly! Safer API design and new cross compilation features.", dated 2025/07/07. The post announces v3; the word "released" was not found. | Fetched page | Verified (as an announcement) | 1 Nov 2026 |
| Temporal is enabled by default in Node.js 26 | Node.js 26.0.0 release | "The Temporal API is now enabled by default in Node.js 26." | Fetched page | Verified | 1 Nov 2026 |
| Safari has no Temporal; WebKit bug 320164 is a duplicate of an open bug | Bug 320164 | "RESOLVED DUPLICATE of bug 223166" | Fetched page | Verified (as of 31 Oct 2026) | 1 Nov 2026 |
| WebKit bug 223166, which tracks Temporal in JavaScriptCore, is open | Bug 223166 | "[JSC] Implement Temporal": "REOPENED" | Fetched page | Verified (as of 31 Oct 2026) | 1 Nov 2026 |
| The current MCP specification revision is 2026-07-28 | Release 2026-07-28 | The release page is titled "Release 2026-07-28" and marked "Latest"; the repository is now modelcontextprotocol/modelcontextprotocol
|
Fetched page | Verified (as of 31 Oct 2026) | 1 Nov 2026 |
| A PyPI pending trusted publisher can be set up before the project exists | PyPI documentation | The pending publisher page is "under your account sidebar instead of any project's sidebar (since the project doesn't exist yet)" | Fetched page | Verified | 1 Nov 2026 |
| crates.io trusted publishing needs the first release published manually | Rust blog, 11 Jul 2025 | "To get started with Trusted Publishing, you'll need to publish your first release manually." | Fetched page | Verified | 1 Nov 2026 |
| npm trusted publishing needs npm 11.5.1 and Node.js 22.14.0 or later | npm documentation | "Trusted publishing requires npm CLI version 11.5.1 or later and Node version 22.14.0 or higher." The page does not say whether the package must already exist. | Fetched page | Verified | 1 Nov 2026 |
Every check below is reproduced by research/verification/verify_claims.py, whose committed output is expected_output.txt. The docs workflow reruns it on every pull request and compares the output byte for byte.
| ID | Claim | Result | Method | Status | Verified |
|---|---|---|---|---|---|
| C01 | All 168 "last" and "nearest" rules have exactly 71 years of 53 weeks in each of two 400-year windows | Every rule has 71 long years in 1601–2000 and 2001–2400 | Script check | Verified | 1 Nov 2026 |
| C02 | 400 Gregorian years hold exactly 20,871 weeks | 146,097 days = 20,871 weeks | Script check | Verified | 1 Nov 2026 |
| C03 | NRF 53-week years in 2016–2030 are 2017, 2023 and 2028 | [2017, 2023, 2028] | Script check | Verified | 1 Nov 2026 |
| C04 | NRF fiscal 2023 runs from 29 Jan 2023 to 3 Feb 2024 | 2023-01-29 to 2024-02-03, 371 days | Script check | Verified | 1 Nov 2026 |
| C05 | NRF fiscal 2024 starts on 4 Feb 2024 | 2024-02-04 | Script check | Verified | 1 Nov 2026 |
| C06 | 364 days before 4 Feb 2024 is 5 Feb 2023, in week 2 of NRF fiscal 2023 | 2023-02-05, week 2 | Script check | Verified | 1 Nov 2026 |
| C07 | After a 53-week year, the same fiscal position is 371 days back | Week 1 day 1 of fiscal 2024 minus 371 days = 2023-01-29 | Script check | Verified | 1 Nov 2026 |
| C08 | NRF's 2017 restatement moves the first comparable week from 29 Jan–4 Feb to 5–11 Feb | Matches | Script check | Verified | 1 Nov 2026 |
| C09 | Apple (last Saturday of September) has 53-week years in 2017, 2023 and 2028 (2016–2030) | [2017, 2023, 2028] | Script check | Verified | 1 Nov 2026 |
| C10 | Broadcast months are 4 or 5 weeks in 2020–2031 | Full month and quarter table in the output | Script check | Verified | 1 Nov 2026 |
| C11 | Broadcast 2024 months run 4-4-5 in every quarter | [4, 4, 5] × 4 | Script check | Verified | 1 Nov 2026 |
| C12 | Broadcast 2021 Q1 months run 5-4-4 | [5, 4, 4] | Script check | Verified | 1 Nov 2026 |
| C12a | The proposal's "5-4-4 in 2021" for the whole year | Holds for Q1 and Q4 only; Q2 and Q3 run 4-5-4 | Script check | Quote corrected | 1 Nov 2026 |
| C13 | Broadcast 2029 quarters are 12, 13, 14 and 13 weeks | [12, 13, 14, 13] | Script check | Verified | 1 Nov 2026 |
| C14 | Broadcast quarters run 12 to 14 weeks in 2020–2031 | Range 12..14 | Script check | Verified | 1 Nov 2026 |
| C15 | The ISO 8601 week year equals a week-based year starting on the Monday nearest 1 January, 1600–2399 | 800 years, 0 mismatches against date.isocalendar()
|
Script check | Verified | 1 Nov 2026 |
| C16 | Care.com's year and quarter rules give different Q4 ends in 2020, 2021 and 2025–2027 (window 2019–2028) | [2020, 2021, 2025, 2026, 2027]; 2025: 27 Dec 2025 against 3 Jan 2026. Compares two rules as written; Care.com has used a calendar year since fiscal 2019. | Script check | Verified (under the inclusive reading) | 1 Nov 2026 |
| C17 | The C16 result depends on the reading and the window | Strict reading adds 2022; the inclusive reading over 2010–2035 adds 2010, 2014, 2015, 2031 and 2032 | Script check (informational) | Verified (see D11 on the PDR) | 1 Nov 2026 |
| C18 |
date(9999, 12, 31) + timedelta(days=1) raises OverflowError in Python |
OverflowError: date value out of range |
Script check | Verified | 1 Nov 2026 |
| C19 | The NRF rule gives exactly the 53-week years NRF publishes for 2006–2023; NRF lists none after fiscal 2023, so 2028 (C03) is the rule's prediction only | Rule gives [2006, 2012, 2017, 2023]; NRF publishes [2006, 2012, 2017, 2023] | Script check | Verified | 1 Nov 2026 |
These four claims from the research documents have no authoritative source as of 1 Nov 2026. The wiki marks them unverified wherever they appear and does not rely on them for any requirement.
| Claim | Where it appears | What was found | Status |
|---|---|---|---|
| Thai government fiscal years are numbered in the Buddhist Era (CE + 543) | Proposal, naming axis | Only Wikipedia gives the 543-year difference ("543 years ahead of the Gregorian calendar"); no source says fiscal years are numbered this way | Unverified |
| "Many Japanese companies" name April 2025 to March 2026 "FY2025" | Proposal, naming axis | No source found | Unverified |
| "FY 2025-26" naming is common in the UK and Australia | Proposal, naming axis | No source found | Unverified |
| Nepal's fiscal year starts on 16, 17 or 18 July | Proposal and gap analysis | Only a user comment on the Akaunting forum, which says "sometime July 16, or July 17 or July 18" | Unverified |
The Indian FY/AY claim was on this list in the plan (contradiction D10). It now has an official source, which corrects it (see India, ERP and transition years).
- PDR: requirements and the open questions D1 to D12.
- Analysis: the landscape and gap table that use these rows.
-
Testing-Strategy: how the conformance vectors relate to
research/verification/.
fiscalclock is licensed under MIT OR Apache-2.0 (MIT, Apache-2.0). Last reviewed: 31 Oct 2026. Found an error on this page? Report it with the documentation form.