# Document filing and binders: research notes

Date: 2026-10-25. Scope: things that hold loose paper documents for storage, carrying or presenting: ring binders (round, D and slant-D, including view and presentation binders), lever arch files, display books (bound clear sleeves), file folders and file jackets, hanging (suspension) folders, pocket folders, expanding files and wallets, sheet protectors (punched pockets) and file storage boxes. Not index dividers and adhesive tabs (sibling `labels`, "Labels, Tabs & Laminating Supplies"), prong fasteners, binder clips and ring reinforcements (sibling `office-paper-fasteners`), hole punches (sibling `desk-paper-tools`), envelopes (sibling `cards`), planner and organiser binders sold as dated goods (sibling `planners`), filing cabinets (furniture). Two boundaries added after the blind check: archival photo sleeves, photo pages for binders and trading-card pages go to sibling `keepsake-storage` ("Photo, Stamp & Memorabilia Storage"), even though they go on rings; document sheet protectors stay here. File storage boxes sold in filing ranges (Leitz files "Expanding Files & Boxes" under Filing) stay here; general lidded storage boxes and crates go to sibling `storage-containers`. Where a binder's own facet touches a sibling's product (a binder cover wide enough to cover tab dividers; a hole pattern that must match a punch) the facet stays here and the product stays with the sibling.

Quote labels: **verbatim** = the sentence in quotation marks was in text I read myself (curl plus HTML stripping, pdftotext on a downloaded PDF, or Shopify product JSON); **fetched excerpt** = a fetch tool summarised or lightly reworded the page; **search excerpt** = the claim came from a search-engine summary because the page itself was not read. A search-excerpt-only number does not go in category.json. Every quote below is verbatim unless labelled otherwise; I did not use WebFetch summaries for any number.

Research constraint: the session's WebSearch budget (200 calls, shared across the parallel runs) ran out after my first four searches. Everything after that came from URLs I already had, links found inside fetched pages, and Shopify JSON endpoints on brand sites. That is why there is no specialist reviewer who measures (none surfaced in the four searches that I could fetch; the "tested" review sites in results are affiliate listicles) and why second brands (Cardinal, Wilson Jones, Pendaflex) are missing. Recorded under "Could not reach".

## Seed

Seed run, output verbatim:

```
=== Example entry (from an unrelated category) ===
category: bedsheets
what this shows: the expert split is often not the number everyone advertises. Thread count is the generic trap here. Weave is what changes how the sheet feels and sleeps.

<example>
{
  "id": "weave",
  "label": "Weave",
  "definition": "The pattern the threads are crossed in, which decides how the sheet feels and how it handles heat.",
  "why_experts_care": "Percale is a simple one-over-one weave that feels crisp and cool and gets softer with washing. Sateen puts more thread on the surface so it feels silky and warmer and shows wear sooner. Thread count, the number most listings lead with, matters far less than which of these two you pick, and above about 400 it is mostly marketing.",
  "kind": "categorical",
  "values": ["percale", "sateen", "linen", "flannel", "jersey"],
  "roles": ["split", "filter"],
  "novice_answerable": true,
  "cold_start_question": "Do you sleep hot, or do you like a sheet that feels smooth and a bit warm?",
  "source": "listing",
  "listing_field_hint": "Usually in the title or the first bullet. Sometimes only in the fabric care tab.",
  "backfill_cost": "low",
  "backfill_note": "When missing, the product photo and the description words 'crisp' or 'silky' usually settle it.",
  "visual": { "chartable": false },
  "priority": { "narrows_set": 4, "cost_to_answer": 1 },
  "evidence": ["wirecutter_sheets", "textile_primer"]
}
</example>

=== Persona ===
A tailor, who thinks in fit, drape and what you can alter afterwards

Ask yourself two things and write the answers under 'Seed' in notes.md:
  1. What is the binders equivalent of the example above?
  2. What would this persona notice first about binders that a typical buyer would not?
Keep what survives the data check. Drop the rest.
```

1. **The binder equivalent of thread count is the ring size, the "1 inch" or "3 inch" in every title.** Everyone compares on it, and it is not the number that decides what you get. Ring shape changes how many sheets that size holds: retailer charts put a 1 in round ring at about 175 sheets and a 1 in D-ring at 220 to 275 (Unikeep; Ring Binder Depot gives 170 to 190 and 225 to 240), and Avery says its EZD D-rings "hold up to 50% more sheets than round rings of the same size". The weave equivalent, the thing that changes the experience, is ring shape plus where it is mounted: round rings sit on the spine and pages do not lie flat; D-rings sit on the back cover and they do. **Kept** as `ring_type` with `ring_size_in` beside it, and the `sheets_per_ring_inch` derived metric to check a stated capacity. The capacity question is asked in sheets, not inches, for this reason.
2. **The tailor notices fit first: does the page fit the cover and do the holes fit the rings.** Three fits survived the data check. Hole pattern: US letter uses three holes 4.25 in (108 mm) apart, ISO countries two holes 80 mm apart or four at 80 mm, and they do not interchange (Wikipedia ring binder and hole punch pages; ISO 838 text). Page size: A4 is 210 by 297 mm against letter's 216 by 279 mm, so A4 is taller and narrower; Avery's own FAQ wrongly says 8.5 by 11 in "is also called A4". Cover overhang: sheet protectors "stick out a little further than paper" and divider tabs stick out further still, so Avery sells wider covers (Avery FAQ). And "what you can alter afterwards" survived as the rings-versus-sleeves distinction: a ring binder takes pages in and out, a display book's sleeves are bound in (Leitz files them as separate product lines). **Kept**: `paper_format` as a split, `holding_method` as split 1, cover width folded into `durability_tier` (only Avery documents it). **Dropped**: a separate "cover overhang" facet (one brand; no retail field), and "can you replace the ring mechanism" (no source found that any consumer binder offers it).

## Sources and what each supports

### Standards bodies and the hole patterns

**ISO 838:1974, Paper: holes for general filing purposes (iTeh preview PDF, pdftotext)**
https://cdn.standards.iteh.ai/samples/5207/c7c11e2022304b368909f866a90a5c7b/ISO-838-1974.pdf
- verbatim: "distance between centres of holes : 80 + 0,5 mm", "diameter of holes : 6 * 0,5 mm" (the ± renders as + and *), "distance from the centre of the holes to the nearest edge of the sheet : 12 + 1,0 mm".
- verbatim: "In general, it does not apply to sheets or documents intended for special filing systems (loose leaf binders, etc.)."
- verbatim: member bodies that "expressed disapproval of the Recommendation on technical grounds : Sweden ... U.S.A."
- Supports: the 80 mm two-hole pattern; the US never adopted it; the standard itself excludes loose-leaf binders, so binder hole patterns beyond two holes are de facto. Confidence high.

**Wikipedia, Hole punch (Standards section)**
https://en.wikipedia.org/wiki/Hole_punch
- verbatim: ISO 838 "specifies two holes, with centers 80 ± 0.5 mm apart, and located 12 ± 1 mm from the nearest edge".
- verbatim: 888: "Two holes are punched in accordance with the standard, plus two additional holes located 80 mm to the outside of the standard holes ... while still allowing 4-hole paper to fit 2-ring binders."
- verbatim: "Unlike ISO 838, there appears to be no well-established official specification for ANSI paper hole patterns, and instead they are de facto standards".
- verbatim: US letter: "The holes are positioned symmetrically, with the centers 4 + 1 ⁄ 4 inches (108 mm) apart." Half-letter "three holes are 2 + 3 ⁄ 4 inches (70 mm) apart". Legal 4-hole "centers 3 + 1 ⁄ 2 inches (89 mm) apart". Swedish triohålning "21 mm , 70 mm and 21 mm apart".
- verbatim: hole diameter "typical values being 1 ⁄ 4 to 5 ⁄ 16 inch (6 to 8 mm)".
- Supports: `paper_format` values and the hole-pattern grammar. Confidence high for ISO (matches the standard), medium-high for US de facto figures.

**Wikipedia, Ring binder**
https://en.wikipedia.org/wiki/Ring_binder
- verbatim: "The North American de facto standard spacing is 4.25 inches (108 mm) between holes."
- verbatim: "Countries that use ISO paper sizes ... use a two- or four-hole system for holding A4 sheets"; "The ISO standard two holes are 80 millimetres (3.1 in) apart, according to ISO 838."
- verbatim: "In North America , the rings themselves come in a variety of sizes, including 0.5, 1, 1.5, and 2 inches".
- verbatim: Leitz "created the lever arch file, a standing binder with a riveted lever arch mechanism".
- verbatim: "Most binder covers are made of three pieces ... three pieces of board held together with sheets of vinyl or other materials".
- Supports: hole spacing (second source, though the same publisher as Hole punch), lever arch origin, cover construction. Confidence medium-high.

**"Hole punch measurements" PDF (an unattributed web PDF, pdftotext)**
https://img1.wsimg.com/blobby/go/db112521-e536-400b-b453-631e78951ba0/downloads/78851783429.pdf
- verbatim: 3-hole "holes ... will be 108mm apart or 4 and a half inches apart" (108 mm is 4.25 in; the inch figure is wrong). "4-hole 888 ... equally spaced at 80mm". "4-hole legal ... spaced 89mm apart".
- Supports: an independent third source for 108 mm, 80 mm and 89 mm. Low quality; the 4.5 in slip is logged. Not cited in category.json.

**Wikipedia, Punched pocket**
https://en.wikipedia.org/wiki/Punched_pocket
- verbatim: "The most commonly used material for punched pockets is polypropylene."
- verbatim: "The thinnest pockets may be less than 2 mil ( 0.051 mm ), while the thickest are over 4 mil ( 0.10 mm )."
- verbatim: sizes "A4 ( 210 mm × 297 mm; 8.3 in × 11.7 in ) for Europe, or 8.5 by 11 inches (216 by 279 mm) for the United States"; "top-loading or side-loading".
- Supports: sheet protector material and sizes; A4 vs letter dimensions. The mil range is single-source and stays here.

**German Wikipedia, Aktenordner (lever arch file)**
https://de.wikipedia.org/wiki/Aktenordner
- verbatim: "Am verbreitetsten sind Ordner für das Papierformat DIN A4 mit zwei Ringen und einer Rückenbreite von 80 mm ... die ca. 600 Blätter mit einer Grammatur von 80 g/m² aufnehmen können, sowie schmalere Ordner mit einer Rückenbreite von 55 mm für ca. 350 Blätter."
- verbatim: "Für die Aufnahmekapazität eines Aktenordners ist allerdings nicht allein die Rückenbreite maßgeblich, sondern vor allem die Füllhöhe" ... "bei Papier von 80 g/m² mit etwa 0,1 mm pro Blatt gerechnet werden, wobei stärkere Papiere sowie zusätzlich eingelegte Register oder Hüllen die tatsächliche Blattzahl verringern."
- verbatim: "In Deutschland und den meisten anderen Ländern mit Papier im DIN-A4-Format ist eine Zweifachlochung im Abstand von 8 cm üblich."
- Supports: lever arch capacity (80 mm ≈ 600, 55 mm ≈ 350 sheets of 80 g/m²), capacity depends on fill height not spine width, dividers and sleeves reduce sheet count. Confidence medium-high.

### Archival and preservation (the governing standards for what the product does to documents)

**Library of Congress, Ask a Librarian: How do I preserve my photographs and negatives?**
https://ask.loc.gov/preservation/faq/422212
- verbatim: "Suitable plastic enclosures are made of uncoated polyester film, uncoated cellulose triacetate, polyethylene, and polypropylene."
- verbatim: "Storage materials must pass the ANSI Photographic Activity Test (PAT) which is noted in supplier's catalogs."
- verbatim: "Polyethylene or polypropylene photo sleeves that fit into ring binders offer an easy solution."
- verbatim: "Avoid albums with colored pages and "magnetic" or "no stick" albums."
- Supports: `archival_safe`, `cover_material`, the PAT. Confidence high.

**US National Archives, Storing family papers and photographs**
https://www.archives.gov/preservation/family-archives/storing
- verbatim: "sleeves made of stable plastics such as polyester, polypropylene or polyethylene."
- verbatim, under "Materials to Avoid When Storing Family Papers": "Unknown plastics or polyvinyl chloride (PVC) plastics"; also "Non-stainless steel staples and paper clips".
- verbatim: boxes "made of board or folder stock that is lignin-free and acid-free or buffered. Have passed the PAT if storing photographs"; "Don’t overstuff the box."
- verbatim: "There are a variety of binding styles and types that are safe, including spiral, ring binders".
- Supports: PVC to avoid (second source with LoC's list of what is suitable), acid-free and lignin-free board, PAT for photos. Confidence high.

**Wikipedia, Photographic Activity Test**
https://en.wikipedia.org/wiki/Photographic_Activity_Test
- verbatim: "Photographic Activity Test ( PAT ) is an ISO standard test detailed in ISO 18916:2025 (E), updated in 2025. Previous versions of the standard were numbered ISO 14523:1999(E)."
- Supports: the standard number for PAT. Confidence medium (Wikipedia; the IPI page fetched as navigation only).

**Keepfiling, Archival safety and what sheet protectors are made of (retailer of archival sleeves)**
https://www.keepfiling.com/archival-safety-a/134.htm
- verbatim: "Plastic enclosures manufactured from polyvinyl chloride ( PVC ) are NOT recommended for archival photographic or document storage. This plastic, often referred to as "vinyl" ... can contain volatile plasticizers (softener) and emit damaging hydrochloric acid as it deteriorates."
- verbatim: "the material in the sheet protector most likely have been smeared or copied on to the sheet protector itself. It happens very easy with laser prints".
- verbatim: smell test "is not 100% safe".
- Supports: why PVC is avoided (plasticiser, print transfer). Seller with an interest; used beside LoC and NARA, not alone. Confidence medium.

**Avery help: Polypropylene sheet protectors are archival safe**
https://www.avery.com/help/article/averys-polypropylene-sheet-protectors-are-archival-safe
- verbatim: "a very chemically stable plastic that is essentially pH neutral (acid free) and contains no plasticizers".
- Supports: polypropylene's archival claim from a maker. Confidence medium.

### Brand spec pages (fields and the order brands list them)

**Avery 79812 Heavy-Duty View 4" binder (product page)**
https://www.avery.com/products/binders/79812
- verbatim title: "Avery® Heavy-Duty View 3 Ring Binder, 4" One Touch EZD® Rings, 4.5" Spine". Spec block: "4" Capacity 780-sheet capacity ... One Touch EZD Ring Includes pockets".
- verbatim: "EZD rings can also hold up to 50% more sheets than round rings of the same size."
- verbatim: "The binder rings are mounted on the back cover to keep your pages flat".
- verbatim: "Nonstick, archival-safe material won't lift ink or toner off printed pages"; "Created with durable, non-stick polypropylene".
- verbatim: "Wide front and back binder panels fully cover standard dividers and sheet protectors".
- Field order Avery lists: ring size, sheet capacity, colour, ring type, pockets. Spine width is in the title.

**Avery 09701 Durable View 3" binder (product page)**
https://www.avery.com/products/binders/09701
- verbatim: "White durable view binders with 3 inch EZD rings hold up to 670 sheets; binder cover has a 3.5" wide spine".
- verbatim, further down the same page: "The 3 inch EZD rings ... hold up to 400 sheets". The page states two capacities for one binder.
- verbatim: pockets "created from a smudge-resistant, PVC-free plastic that won't transfer ink".
- Supports: capacity claims are not reliable even on a maker's own page (judgement); PVC-free and print transfer (second Avery page).

**Avery binders category and FAQ, including the comparison chart**
https://www.avery.com/category/products/binders/
- verbatim chart rows: "Ring shape | EZD has highest page capacity, followed by slant | Round | Slant | EZD" (Economy, Durable, Heavy Duty); "Board thickness | ... | Standard | Thick | Thickest"; "One Touch | ... | No | No | Yes"; "Wider panels | Prevents damage; fully covers sheet protectors and dividers | No | Yes | Yes"; "Pockets | Two | Two | Four".
- verbatim: "Avery classifies binders into three categories: Economy, Durable, and Heavy-Duty."
- verbatim: "Avery binders are made with thick cardboard wrapped in non-stick polypropylene, which is durable and PVC-free, while the spines and rings are made of steel."
- verbatim (wrong): "8.5" by 11" paper is also called "A4" and "letter size,"". Logged as a correction against the source.
- verbatim: covers "are slightly wider than normal. This is so that they cover sheet protectors (which stick out a little further than paper) and the tabs on dividers."
- Supports: `durability_tier` values, ring order, cover width. One brand's vocabulary; the tiers stand as a description of how one leading brand ladders its range.

**Avery blog: the best binders for school**
https://www.avery.com/blog/the-best-binders-for-school-at-every-age-and-level/
- verbatim: "the average textbook is 200 to 400 pages, so a durable, 2-inch binder with a 500-sheet capacity will cover most textbooks."
- verbatim: "Durable and heavy-duty binders are best constructed to cope with hundreds of sheets, which get quite heavy."
- verbatim: teachers "recommended between 1/2″ and 1-1/2″ wide three-ring binders for their elementary classes."
- Supports: the over-500 branch's durability leg.

**Leitz (ACCO) UK, filing range and lever arch files**
https://www.leitz.com/en-gb/products/filing--archiving/lever-arch-files/
- verbatim: "Leitz 180° Lever Arch Files with patented 180° mechanism open 50% wider than other file types ... They can hold between 350 and 600 A4 sheets."
- verbatim (ring binders page): "Leitz Ring Binders are ideal for organisation where space is limited and for presenting or storing documents on the move. With a slimline design they are convenient to carry ... Available in two and four ring varieties".
- verbatim (site navigation, Filing): "Lever Arch Files Ring Binders Presentation Binders Suspension Files Spine Labels Indices & Dividers Pockets & Folders Hole Punches Card Files & Folders Display Books Divider & Signature Books Expanding Files & Boxes".
- Supports: lever arch capacity (second source with de.wikipedia), the trade's own division of the category into rings, folders, suspension files and display books, and the slim-ring-binder-for-carrying trade-off.

**Smead (US file-folder maker), product JSON from smead.com (Shopify endpoints)**
https://www.smead.com/products/standard-file-folders-1-3-cut-tab and the collections `top-tab-file-folders`, `hanging-file-folders`, `expanding-files`
- verbatim: "Includes 100 letter size folders (11-5/8" W x 9-1/2" H overall, 9" H body) in manila with a 1/3-cut tab in assorted positions ... Durable 11 point stock folders are perfect for files that are seldom accessed. Scored for 3/4” expansion."
- verbatim (hanging folders): "letter size hanging file folder ... features a 1/5-cut repositionable poly tab and coated rod tips that slide easily in file drawers"; "11 pt. stock".
- verbatim (file jackets): "Expands 2" for greater storage capacity ... closed sides to keep your materials from slipping out".
- verbatim (poly two-pocket folders): "Each pocket holds up to 50 sheets ... Acid free, PVC free."
- Tally I ran over the three collections (143 products). Size option values: Letter on 117 products, Legal on 83 (some offer both). Mentions in titles and descriptions (a product can mention more than one): tab cuts 1/3 (37), 2/5 (17), 1/2 (11), straight (17), 1/5 (13); stock 11 pt (32), 14 pt (3), 18 pt (1), 25 pt (3); expansion 3/4 in (14), 2 in (20), 7/8 in on expanding files (13), up to 5-1/4 in.
- Field order Smead lists: size, colour, tab cut and position, stock in points, expansion, recycled content.
- Supports: folder facets (`tab_cut`, `folder_expansion_in`, `folder_stock_pt`), and that letter versus legal splits the US folder catalog almost in half.

**Wikipedia, File folder**
https://en.wikipedia.org/wiki/File_folder
- verbatim: "In the United States, letter and legal sizes are common."
- verbatim: tab cuts "Straight cut ... 1 ⁄ 3 cut ... 1 ⁄ 5 cut ... 2 ⁄ 5 cut ... 1 ⁄ 2 cut".
- verbatim: "hanging folders are used to file one or more manila folders, and it is not a common practice to put loose sheets directly into hanging folders."
- Supports: tab cut values (second source with Smead), letter and legal, hanging folder role.

### Retailer capacity charts (two independent sellers)

**Unikeep, 3 ring binder sizes chart**
https://www.unikeep.com/binder-sizes-chart/
- verbatim: Round: "1 inch 175 Sheets ... 2 inches 375 Sheets 3 inches 460 Sheets". Standard D: "1 inch 275 Sheets ... 2 inches" 540 Sheets 3 inches 670 Sheets 4 inches 780 Sheets 5 inches 1300 Sheets". Slanted D: "0.5 inch 120 Sheets 1 inch 220 Sheets ... 2 inches 480 Sheets 3 inches 600 Sheets 4 inches 725 Sheets 5 inches 975 Sheets".
- verbatim: "Round rings attach to the spine and your papers will not lay flat with these."
- verbatim: "The slanted "D" rings tend to be more durable but they cannot hold as many pages as the standard "D" ring."
- Note: the D-ring figures at 3 and 4 in equal Avery's stated capacities (670, 780), so they may be copied from Avery.

**Ring Binder Depot, How to choose the right 3 ring binder**
https://ringbinderdepot.com/blogs/articles/how-to-choose-the-right-3-ring-binder
- verbatim chart: Round "1″ 170 – 190 ... 2″ 340 - 380 3″ 510 - 570". D-ring "1″ 225 - 240 ... 2″ 450 - 480 3″ 675 - 720". Slant-D "1″ 200 - 230 ... 2″ 400 - 460 3″ 600 – 690".
- verbatim: "D-Ring Binders can hold up to 30% more paper than a standard Round Ring Binder"; slant-D "up to 25% more"; "the slant-D ring binder holds about 5% fewer pages than the standard D ring binder."
- verbatim: "To determine the sheet capacity of a D-Ring binder, always measure the straight part of the binder ring."
- verbatim: "The capacity mentioned below is the limit to which the binder closes comfortably."
- verbatim: "the round rings are mounted to the spine ... causing your papers/ documents to not lay flat."

The two charts agree within about 10 percent at 1 and 2 in for every ring type and disagree on round rings at 3 in (460 vs 510 to 570). Ring order is the same in both and in Avery's chart: straight D, then slant D, then round.

### Search excerpts only (not used for numbers)

- deskrated.com, findthisbest.com "tested" binder lists (search excerpt): Avery Heavy-Duty View, Amazon Basics 3 in D-ring 2-pack "600-sheet capacity", Staples Better Binder 2 in "up to 540 sheets", Oxford ONE-Touch "up to 530 sheets". Useful only as evidence that retail titles carry ring size, ring shape and sheet capacity. Affiliate lists; not cited.

### Could not reach

WebSearch budget exhausted after four searches (see top). Staples (403), Wilson Jones and ACCO (connection refused), Cardinal/TOPS (redirects to tops-products.com, product JSON 404), Pendaflex (no response), Officeworks (405), Ryman (403), NEDCC storage-enclosure leaflet (403), Image Permanence Institute PAT page (navigation only), Archival Methods (empty), Leitz product detail pages (loaded by script, not in HTML). Amazon was not attempted; earlier registers record that it blocks fetches.

## Data points used for derived metrics

- After the blind check (2026-10-25) the bands below were replaced. Full per-size figures: Unikeep round 175/in at 1 in, 187.5 at 2 in, 153 at 3 in; Unikeep D 275 at 1 in, 320 at 1.5 in (480 sheets), 270 at 2 in, 223 at 3 in, 195 at 4 in, 260 at 5 in; RBD round 170 to 190 at every size, D 225 to 240. Cardinal round-ring Amazon titles (read in the checker's saved copy of amazon.com `s?k=3+ring+binder`): 1 in "Holds 225 Sheets", 1.5 in "Holds 350 Sheets" (233/in), 2 in "Holds 475-Sheets" (237/in), 3 in "Holds 625 Sheets" (208/in). The JSON now says round 153 to 190 and D about 195 to 320 across the two charts, falling per inch at 3 in and up, with Cardinal's 208 to 237 named as a brand that states more; a figure outside the charts is a prompt to check, not a verdict. `ring_size_needed_in` now looks up the lower of the two charts per size instead of dividing by a per-inch rate.
- Original text, kept for the audit trail: `sheets_per_ring_inch` (stated capacity divided by ring size): round 175 per in at 1 in (Unikeep) and 170 to 190 (Ring Binder Depot); straight D 225 to 275 at 1 in (Ring Binder Depot 225 to 240, Unikeep 275); slant D 200 to 230 (Ring Binder Depot) and 220 (Unikeep). Avery's own pages give 670 at 3 in (223 per in) and 780 at 4 in (195 per in), and also 400 at 3 in (133 per in) on the same page as 670. Bands used in category.json: round about 170 to 190, D-type about 200 to 275. A stated figure well above the band for its ring type is the flag.
- `ring_size_needed_in`: sheets to hold divided by the band above. 500 sheets in round rings → about 2.6 to 2.9 in, so 3 in; in D-rings → about 1.8 to 2.5 in, so 2 or 2.5 in. Avery's own textbook advice ("2-inch binder with a 500-sheet capacity") matches the D-ring band.
- `price_per_100_sheets`: price / sheet_capacity × 100. No sourced range; the metric only compares within the result set.

## Against the existing add-on schema

The add-on `supplies/stationery/add-ons/binder.jsonc` has `ring_type` (enum round, d_ring, slant_d, none, not_applicable, unspecified), `sizing.ring_size_inch` and `sizing.sheet_capacity`. The stationery standard is empty; the supplies standard has `high_signal_markdown` and `sizing` (size_stated, pack_count, dimensions, capacity, weight). Kinds per `zamana-expertise/AGENTS.md` rule 4. Proposals only; nothing edited.

| Register facet | Current add-on field | Proposed kind | Proposal |
|---|---|---|---|
| `format` | none | vertical anchor | Add `filing_format` enum: ring_binder, lever_arch_file, display_book, file_folder, file_jacket, hanging_folder, pocket_folder, expanding_file, document_wallet, sheet_protector, storage_box. The leaf mixes these and nothing in the schema tells them apart; `holding_method` derives from it. |
| `holding_method` | none | derived, no field | Derive from `filing_format`. Do not store. |
| `ring_type` | `ring_type` | hard filter | Keep. Add `lever_arch` (a different mechanism with its own capacity scale). Drop one of `none` and `not_applicable`; they say the same thing for a folder. |
| `ring_size_in` | `sizing.ring_size_inch` | sizing | Keep. Also accept a metric spine or ring size (lever arch files are sold as 50/55/80 mm spines). |
| `sheet_capacity` | `sizing.sheet_capacity` | category quality currency | Keep, but augment from ring size and type when missing, and flag stated values outside the per-inch band. Also use for folders and pockets (Smead states "holds up to 50 sheets"). |
| `capacity_band` | none | derived, no field | Derive from `sheet_capacity`. |
| `paper_format` | none (only `size_stated` text) | hard filter | Add `paper_format` enum: letter_3hole, legal, a4_2hole, a4_4hole, half_letter, a5, tabloid. Buyers filter on it literally and a mismatch means the pages do not fit. |
| `archival_safe` | none | hard filter | Do not add as a claim field (rule 5 kills claim vocabularies). Derive it from `cover_material` plus "PVC-free" or "acid-free" in the high-signal markdown. |
| `cover_material` | none | hard filter | Add enum: polypropylene, pvc_vinyl, paperboard_pressboard, fabric_or_leather, other. This is the fact that decides archival safety and print transfer. |
| `durability_tier` | none | none (markdown) | Leave to `high_signal_markdown`; tiers are brand vocabulary (Avery) and board thickness is never stated as a number. |
| `view_cover` | none | none (photo) | Visible in the photo; leave to the image pipeline per rule 1. |
| `spine_width_in` | `sizing.dimensions.depth` | sizing | Already covered by the standard's dimensions. No new field. |
| `tab_cut` | none | hard filter | Add enum straight, 1/2, 1/3, 2/5, 1/5 for folders; buyers match an existing drawer of folders. |
| `folder_expansion_in` | none | sizing | Add `sizing.expansion_inch`. Smead sells the same folder in 3/4, 1, 2 and 3 in expansions. |
| `folder_stock_pt` | none | category quality currency (folders only) | Add `stock_thickness_pt`. It is the number Smead leads with for folder durability. |
| `sleeve_count` | none (`sizing.capacity` with count_items could hold it) | sizing | Use `sizing.capacity` with unit count_items for display books. |

Noise in the current add-on: nothing large. The `ring_type` comment ("D-ring holds more at the same stated size") is right and is the register's seed finding. `unspecified` plus `null` duplicate each other.

## Branches

Trace updated after the blind check (2026-10-25). Split 1's third value is now `display book` (was `sleeves`).

- holding_method = rings → ask capacity_band, ring_type, paper_format; tab_cut, folder_expansion_in, folder_stock_pt, sleeve_count irrelevant. Chain: ring size and shape set capacity (Unikeep, Ring Binder Depot, Avery 79812); rings need a matching hole pattern (Wikipedia hole punch: "de facto standards", ISO 838 80 mm vs US 108 mm). Tab cut, expansion and stock are folder properties (Smead; Wikipedia file folder); sleeve count is a display-book property. Sheet protectors belong here: they are punched to go on rings, so their buyers need ring type and hole pattern. SUPPORTED.
- holding_method = folders → ask format, paper_format, folder_expansion_in; ring_type, ring_size_in, sleeve_count irrelevant. Chain: "folders" still leaves seven types that do different jobs (hanging folders "slide easily in file drawers" and hold manila folders, Smead and Wikipedia file folder; file jackets have "closed sides to keep your materials from slipping out", Smead; file boxes are storage), so `format` is asked first through its drawer / carrying / box question. US folders come in letter and legal (Wikipedia file folder; Smead recount 124 letter, 89 legal, 76 both of 143); Smead states expansion on folders, jackets, hanging and expanding files. No rings, so ring facets cannot apply. SUPPORTED. The tab_cut leg was removed: pocket folders, wallets and file boxes have no cut tab, and tab_cut stays a filter rather than a next question.
- holding_method = display book → ask sleeve_count; ring_type, ring_size_in, tab_cut, folder_expansion_in irrelevant. Chain: Itoya's ProFolio page says its sleeves "are fastened solidly to the cover with black anodized metal rivets" and "24 PolyGlass sheets allow for up to 48 inserts", so the bound sleeve count is the page limit; Leitz lists "Display Books" apart from "Ring Binders". SUPPORTED by one maker's page plus the Leitz range split. The archival_safe leg was removed: archival_safe is already split 4 and applies to sheet protectors on the rings branch just as much.
- capacity_band = over 500 sheets → ask ring_type. Chain: round rings top out at about 460 (Unikeep) to 510 to 570 sheets (Ring Binder Depot) at 3 in, while D-ring binders come up to 5 in (Unikeep chart; Avery lists rings to 5 in on Durable and Heavy-Duty) and lever arch files hold 350 to 600 A4 sheets (Leitz, de.wikipedia), so above 500 the ring type decides whether it fits at all. SUPPORTED. The durability_tier leg was removed: Avery's "hundreds of sheets, which get quite heavy" covers 200 to 500 equally, and lever arch files sit outside Avery's tiers.
- archival_safe = yes → ask cover_material. Chain: LoC lists the suitable plastics (polyester, polyethylene, polypropylene); NARA lists PVC under materials to avoid; Keepfiling (a seller) says PVC lifts print. SUPPORTED.
- paper_format: no branches. Each answer narrows the same facets the same way.

Answer-to-value rules (stated so every answer maps to a facet value):
- Split 1 offers "Punched into rings", "loose in folders", "a bound display book" → `rings`, `folders`, `display book`. A buyer who says "a binder" or "sheet protectors" maps to rings; "a folder" or "a file" maps to folders; "a display book", "presentation book" or "portfolio with sleeves" maps to display book. "Clear sleeves" alone is ambiguous: punched sleeves for a binder are rings, bound sleeves are a display book.
- Split 2 offers "Under 200 sheets", "a few hundred", "over 500" → `under 200 sheets`, `200 to 500 sheets`, `over 500 sheets`. The 200 edge is ours: it is about what a 1 in ring holds by both charts (Unikeep 175 to 275, Ring Binder Depot 170 to 240). The old "count each protector or divider as two or three sheets" multiplier was ours and has been dropped from the JSON; the definition now says only that sleeves and dividers take more space (de.wikipedia). A buyer who gives a ring size instead (school lists do, Avery quotes teachers asking for "between 1/2″ and 1-1/2″") skips the question (`ring_size_stated`): look the size up in the lower of the two charts for the ring type, and use round when the type is unknown (our rule).
- Split 3 offers "Letter, legal, A4, A5, or half-letter" → `US letter`, `US legal`, `A4 two-hole` or `A4 four-hole`, `A5`, `half-letter`. "A4" maps to `A4 two-hole` unless the buyer's pages already have four holes or they want a four-ring binder, because four-hole (888) paper fits two-ring binders but not the reverse (Wikipedia hole punch; the hole punch PDF). "Half-size" alone is ambiguous: ask whether the pages are 5.5 by 8.5 in (half-letter, three holes 70 mm apart per Wikipedia) or A5 (an ISO size; de.wikipedia says A5 ring books often use four-hole systems). Avery's FAQ calls 5.5 by 8.5 in paper "A5", which is wrong.
- Split 4 is yes or no → boolean.
- `format` (asked on the folders branch) asks "For a file drawer, carrying around, or a storage box?": drawer → `file folder` or `hanging folder`; carrying → `file jacket`, `pocket folder`, `document wallet` or `expanding file`; box → `file box`. The grouping is ours, from what each maker says the type does (Smead hanging folders slide in file drawers; Smead jackets keep papers from slipping out).
- `durability_tier` (not a split) asks "Light use, frequent use, or heavy long-term use?", Avery's own tier labels ("For light use", "For frequent use", "For extended use"): light → `economy`, frequent → `durable`, heavy long-term → `heavy-duty`. The old "carried in a bag" wording had no source.

## Trimmed detail

- `ring_type`: Ring Binder Depot says to measure a D-ring's size along its straight side, so a 1 in D and a 1 in round ring do not have the same internal space; that is part of why D-rings hold more at the same stated size.
- `ring_type`: Unikeep and Ring Binder Depot both say slant-D rings are more durable than straight D; neither gives a test. Avery calls its straight D (EZD) its highest-capacity ring and puts it on its top tier.
- `paper_format`: ISO 838 also says the hole axis may run along the short or long edge; the Swedish four-hole system and the Japanese 30-ring A4 system exist but are national.
- `paper_format`: A4 is about 11.7 in tall, 0.7 in taller than letter, and 0.2 in narrower. An A4 sheet in a letter binder overhangs the bottom of a 9 by 12 in cover by little, but the holes still do not match.
- `archival_safe`: NARA also lists non-stainless steel staples and paper clips as materials to avoid; that belongs to the fasteners sibling.
- `durability_tier`: Avery's Heavy-Duty tier adds One Touch boosters (one press opens all rings) and four pockets; Durable adds slant rings and DuraHinge/DuraEdge; Economy is round rings, two pockets, black or white.
- `lever arch`: Leitz says its 180° mechanism opens "50% wider than other file types"; marketing claim, not used.
- Sheet protectors range from under 2 mil to over 4 mil per Wikipedia; single source, so no thickness facet. Heavier protectors take more ring space, which is the practical reason the capacity question asks buyers to count sleeves extra.

## Safety and health

Rewritten after the blind check (2026-10-25). The earlier text said no consumer-safety standard governs the category; that was wrong. What applies is chemical limits on the product, not a hazard standard for its use.

**Commission Regulation (EU) 2018/2005, REACH Annex XVII entry 51** (EUR-Lex returned an empty 202 challenge to curl; read from the Internet Archive snapshot https://web.archive.org/web/20240621175445/https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32018R2005, stripped text)
- verbatim: "3. Shall not be placed on the market after 7 July 2020 in articles, individually or in any combination of the phthalates listed in column 1 of this entry, in a concentration equal to or greater than 0,1 % by weight of the plasticised material in the article."
- verbatim: "'plasticised material' means any of the following homogeneous materials: — polyvinyl chloride (PVC), polyvinylidene chloride (PVDC),polyvinyl acetate (PVA), polyurethanes, — any other polymer ... — surface coatings, non-slip coatings, finishes, decals, printed designs, — adhesives, sealants, ..."
- Exemptions in paragraph 4: articles exclusively for industrial or agricultural use or the open air, aircraft, motor vehicles, articles placed on the market before 7 July 2020, laboratory measuring devices, food-contact materials, medical devices, electrical and electronic equipment, and others of that kind. None covers consumer stationery.
- Phthalates: DEHP, DBP, BBP, DIBP.

**ECHA, Phthalates hot topic** (echa.europa.eu returned 403; read from https://web.archive.org/web/20250108090416/https://echa.europa.eu/hot-topics/phthalates)
- verbatim: "DEHP, DBP, DIBP and BBP are restricted in a wide range of products since July 2020. These include for example children's swimming aids, flooring, coated fabrics and paper, recreational gear, mattresses, footwear, and office supplies."

**Wikipedia, Phthalates** (https://en.wikipedia.org/wiki/Phthalates)
- verbatim: "Since 7 July 2020, entry 51 of Annex XVII of REACH has limited DEHP, DBP, BBP and DIBP to 0.1% by weight of the plasticised material in all articles placed on the EU market, not only toys."
- Second source for the 0.1% and the date.

**US lead limit for children's products**
- 15 U.S.C. 1278a (LII, https://www.law.cornell.edu/uscode/text/15/1278a), verbatim: "any children's product ... that contains more lead than the limit established by paragraph (2) shall be treated as a banned hazardous substance" and "(C) 100 parts per million ... substituting '100 parts per million' for '300 parts per million'".
- CPSC Total Lead Content (cpsc.gov returned 403; read from https://web.archive.org/web/20260208100552/https://www.cpsc.gov/Business--Manufacturing/Business-Education/Lead/Total-Lead-Content), verbatim: "declares children's products that contain more than 100 ppm lead in an accessible component to be a banned hazardous substance".
- 16 CFR 1200 (eCFR renderer API, https://www.ecfr.gov/api/renderer/v1/content/enhanced/current/title-16?part=1200), verbatim: "A general use product means a consumer product that is not designed or intended primarily for use by children 12 years old or younger", and general furnishings "that often are found in children's rooms or schools would not be considered children's products unless they are decorated or embellished with a childish theme ... are sized for a child, or are marketed to appeal primarily to children."
- Reading (ours): an ordinary binder is a general use product; a binder themed, sized or marketed for children 12 and under is a children's product and falls under the 100 ppm limit. I did not find a CPSC page that names binders. I did not check the CPSIA phthalate rule, which covers toys and child care articles, so the register says nothing about it.

California Proposition 65 warnings on vinyl school supplies are still a hypothesis without a source (WebSearch was exhausted again in this session), so nothing about them is in the register. The archival standards stay where they were: ISO 18916 (PAT) and the LoC and NARA plastics guidance, in `archival_safe` and `cover_material`.

## Corrections

- Against a source: Avery's FAQ says 8.5 by 11 in paper "is also called A4". It is not; A4 is 210 by 297 mm (Wikipedia punched pocket gives both sizes). The register says letter and A4 do not interchange.
- Against a source: the hole punch PDF gives 108 mm as "4 and a half inches"; 108 mm is 4.25 in. The register uses 4.25 in (108 mm) from both Wikipedia pages.
- Against a search excerpt: the first search summary said the US three holes are "4.25 inches between outer holes". The fetched pages say 4.25 in between adjacent centres (8.5 in outer to outer). The register uses the fetched wording.
- Against a source: Avery 09701 states both 670 and 400 sheets for the same 3 in binder. The register cites this as the reason to check capacity per ring inch rather than trust the figure.

## Script and schema notes (2026-10-25)

- The brief asked for `"vertical": "supplies"`, but `schema.json` allows only formulations, machines, fashion, furnishing and other, so validate.py rejects `supplies` (`schema vertical: 'supplies' is not one of [...]`). With it the register would publish as `invalid`. I set `"vertical": "other"`, as most of the other Supplies runs finished today did; `catalog.json` still carries the real vertical (`supplies`) and `publish.py` groups by the catalog, not the JSON. The fix belongs in the skill's schema enum; I did not edit it.
- validate.py, render.py and viewer.py ran clean. `tests/viewer-browser.py` on a temporary copy passed 6 of 6 (1380, 768, 390 px; light and dark; offline). First screen at 1380 light read by me: tree and priority map legible, no overflow.
- WebSearch hit the session budget (200 of 200) after four searches; research continued from fetched pages and brand JSON endpoints only.

## Corrections (author's STYLE and sourcing pass, 2026-10-25)

- Split 1 rationale said the mechanism "removes two thirds of the leaf"; no source counts the leaf, so it now says only that the mechanism decides which facets apply and that Leitz divides its range the same way.
- Summary said D-rings hold "roughly a third more"; aligned to the sourced 25 to 50 percent used in the judgement.
- `paper_format` said A4 four-hole spacing is ISO 838; ISO 838 is two holes only and four-hole (888) is an extension. Fixed.
- `capacity_band` tied 600 sheets to an 80 mm lever arch; Leitz gives only 350 to 600 without spine widths, so the JSON now says 350 to 600 (de.wikipedia's 55 mm / 80 mm split stays here).
- Folder expansion and stock figures are Smead's only; the text now attributes them to Smead instead of stating them as category norms.
- Removed two unsourced sentences: "new folders usually have to match the cut already in the drawer" and "unstated cheap clear sleeves are often PVC".
- `view_cover`, `tab_cut` and `sleeve_count` moved from `listing` to `researched` (low), because I confirmed them only on brand pages, not on retail listings.

## Corrections after the blind check (2026-10-25)

Report: `check.md` (14 required fixes). WebSearch was exhausted in this session too; new sources came from known URLs fetched with curl (Internet Archive where the live site blocked), and from the author's and the checker's saved pages in the scratchpad. All 14 fixes accepted; none rejected.

1. Judgement 6 (CONTRADICTED) rewritten: chemical limits apply. EU REACH Annex XVII entry 51 (Reg. (EU) 2018/2005) has barred DEHP, DBP, BBP and DIBP at 0.1% or more of plasticised material in articles since 7 July 2020 (regulation text, ECHA names "office supplies", Wikipedia Phthalates). The US 100 ppm lead limit (15 U.S.C. 1278a, CPSC) applies only to binders that are children's products under 16 CFR 1200; that scope reading is marked as ours. Added refs `reach_2018_2005`, `echa_phthalates`, `wiki_phthalates`, `us_lead_1278a`, `cpsc_lead`, `cfr_1200`; the REACH limit goes into `cover_material`; vocabulary gains "Phthalate"; the Safety section is rewritten.
2. Split 1 collision fixed: the question is now "Punched into rings, loose in folders, or a bound display book?", the value `sleeves` is now `display book` (in the facet, the branch `when`, and the family name), the `holding_method` definition says sheet protectors count as rings, and an answer rule sends "sheet protectors" to rings.
3. `paper_format` value `half-letter or A5` split into `half-letter` and `A5`; `A4` split into `A4 two-hole` and `A4 four-hole`. Question now "Letter, legal, A4, A5, or half-letter pages?". Why-text says four-hole pages fit two-ring binders but not the reverse, and that A5 ring books often use four holes (de.wikipedia). The 70 mm half-letter figure has only Wikipedia, so it stays in notes and the JSON says only "its own closer three-hole pattern".
4. `durability_tier` corrected against Avery's chart and FAQ: wider covers on both Durable and Heavy-Duty; ring shape no longer defines the tier (09701 is Durable with EZD rings); question changed to Avery's own "light / frequent / extended use" wording ("Light use, frequent use, or heavy long-term use?").
5. Per-inch bands replaced: round 153 to 190 and D about 195 to 320 across the two charts, falling per inch at 3 in and up; Cardinal's stated 208 to 237 per inch round named as a brand that states more; "optimistic" replaced by "a prompt to check, not a verdict". `ring_size_needed_in` now looks up the lower chart per size, and its example says 500 sheets needs 3 in round by Ring Binder Depot but does not fit by Unikeep (460). Added ref `amazon_binders` (checker's saved copy, re-counted by me).
6. D-v-round gap restated as about 30 to 50 percent (RBD up to 30, Avery up to 50, Unikeep's chart 44 to 57) in the summary, `ring_type` and judgement 1. The 25 was RBD's slant-D figure.
7. Judgement 3 note and `archival_safe` now say only NARA names PVC; LoC lists suitable plastics. The print-lifting claim is attributed to Keepfiling, a seller, in `archival_safe`, the sleeve trade-off and judgement 3; no second source found.
8. Split 3 rationale no longer says letter and legal split Smead's catalog in half. My recount of the three collections: 143 products, letter 124, legal 89, both 76 (the checker got 120, 86, 73 with a stricter match); the JSON says Smead sells most folders in both, so size is a variant. `smead_folders` supports line updated.
9. Sources made honest: `ring_type` and `view_cover` moved to `listing` (my count over the checker's saved Amazon page: ring type in 32 of 48 binder titles, View in 19 of 48 and in 22 of 26 Quill binder names; ring type in 16 of 26 Quill names); so `capacity_band` is now derived from listing fields (ring size and ring type) with stated capacity preferred. `sheet_capacity` stays `researched` (23 of 48 Amazon titles, 2 of 26 Quill). `view_cover` backfill cost now none.
10. Four WEAK legs: removed over 500 → durability_tier, display book → archival_safe, folders → tab_cut; sourced display book → sleeve_count with Itoya's ProFolio page (sleeves riveted to the cover, "24 pages for 48 views"), added as `itoya_profolio`.
11. Folders narrowed: `format` is now novice-answerable with "For a file drawer, carrying around, or a storage box?" and is the first next question on the folders branch; the drawer / carrying / box mapping is written out under Branches and marked as ours.
12. Scope boundaries with `keepsake-storage` (photo sleeves and pages, trading-card pages) and `storage-containers` (general storage boxes) added to the scope paragraph at the top.
13. The "two or three sheets per protector or divider" multiplier dropped from the `capacity_band` definition; the 200 edge is recorded as ours (about one 1 in ring by both charts) under Branches.
14. Citation fixes: "slim, convenient to carry" now cites the new `leitz_ring_binders` ref and is removed from `leitz_filing`; "D-rings reach 780 at 4 in" replaced by "D-ring binders come up to 5 in" (Unikeep chart, Avery's tier list), so the single-source 780 and 1300 figures stay out of prose; the hole punch PDF added as `punch_pdf` so 108 mm has a second publisher (its "4 and a half inches" slip is logged above); the single-source 3.5 in spine figure was removed from `ring_size_in`; the D-ring measuring rule is attributed to Ring Binder Depot.
- Summary: "First decide rings, folders or a display book, then match..." (introduced in this pass) reworded ("Rings, folders or a display book decide which facets matter") so it no longer orders the questions outside `branches`.
- Also: `capacity_band` gained `skip_if_known: ring_size_stated` with an answer rule for buyers who give a ring size (check Part B, split 2).