Flattermarken

Overview

Flattermarken (German, singular Flattermarke; English collating marks, black steps or back marks) are printed marks on the spine of folded print sheets whose position shifts uniformly from sheet to sheet, so that missing, duplicated or out-of-order sheets can be spotted ⁶⁷⁸. The barcode libraries Zint and bwip-js expose a "Flattermarken" symbology that turns a digit string into such positional marks; Zint's manual stresses that it "is not a true barcode symbol and requires precise knowledge of the position of the mark on the page" ¹³.

History

Flattermarken belong to the long tradition of bookbinders' gathering aids. The older practice was the signature mark — a letter, number or combination printed at the bottom of the first page of a section so that the binder could order pages and sections correctly; that practice has since been superseded by changes in printing and binding technology and is rarely found in modern books ¹⁰. The positional black-step mark is defined in the Etherington & Roberts Dictionary of Bookbinding and Conservation as a heavy line about 6 points thick and 24 points long on the back of a folded section ⁸. No fetched source gives an inventor or a date of origin for the mark, or for its adoption as a named symbology in barcode software.

Technical specification

The printed mark (bindery practice).

• German Wikipedia describes small black bars, typically 2 × 10 mm, printed on each folded signature at a progressively greater distance from the top edge; correctly gathered, they form a descending staircase on the spine of the book block ⁶. The CTAN collating-marks module describes the same stair-like pattern: each section's mark is shifted by the length of the rule ⁹.
• The Etherington & Roberts dictionary gives a mark about 6 pt thick × 24 pt long, appearing as a diagonal line from head to tail across the back of the text block; a missing or misplaced section breaks the line ⁸.
• Imposition software places these marks automatically. KODAK Preps 11 adds collation marks "to identify the planned sequence of the sections in a product assembly, based on the binding style", with settable width, length and step distance, and several mark styles including numeric indicators ¹¹.

The barcode-library symbology.

• Character set: digits 0–9 only ¹⁴.
• Check digit: none ¹⁴⁵.
• Length: Zint's current manual limits input to 128 digits, and its encoder rejects longer input ¹². bwip-js 4.11.0 allows up to 500 characters ³. The DataFlex and symbology.dev references say "any length" ⁴⁵.
• Encoding (as implemented): each digit takes a 9-module cell. Digits 1–9 place one module-wide bar at position n in the cell, and 0 leaves the cell blank. Zint's table maps 1 → 18 (bar 1, space 8), 2 → 0117, … 9 → 0810, and 0 → 0504 (spaces only) ². bwip-js uses the equivalent table 0018, 0117 … 0810, 0900 for 1…9, 0 ³. Rendering the sample 11099 with bwip-js gives a 45-module-wide symbol with marks in cells 1, 2, 4 and 5 and an empty third cell. An input of just 0 draws nothing.
• Dimensions: Zint's source has a TODO: Find documentation on BARCODE_FLAT dimensions/height comment, so it follows no published dimensional specification ². Zint assigns the symbology ID 28 (BARCODE_FLAT) ¹.

Use cases

• Book production / bindery collation: checking that folded signatures are complete and gathered in the right order (Kollationieren) ⁶⁸⁹.
• Packaging: marks on the edges of folded cartons form continuous lines when stacked. A break shows that cartons from a different print version have been mixed in, which keeps obsolete artwork out of production. Wikipedia says the international term here is "identification mark" ⁶.
• Passports / security documents: Reconnaissance International's glossary describes the collation mark in passports as an added safeguard that makes swapped or removed pages easier to detect ¹².
• Prepress imposition: KODAK Preps generates collation marks automatically, including for jobs that mix binding styles ¹¹.

Implementations

• zint: C, ~810 stars, active October 2026. zint_flat() in backend/postal.c is an encoder (symbology BARCODE_FLAT, CLI -b FLAT), limited to 128 digits ¹².
• bwip-js: JavaScript, ~2.4k stars, active August 2026. Lists flattermarken among its symbologies (bcid: "flattermarken") and implements it as bwipp_flattermarken, which allows up to 500 digits ³.
• CTAN collating-marks (ConTeXt/MetaPost, public domain, by W. Egger) draws collating marks while arranging pages for folding into sections ⁹.

No decoder library was found. Because the mark is read by its position on the page rather than scanned as a bar/space sequence, a general-purpose barcode decoder has nothing to decode ¹.

Comparison

• Flattermarken vs. signature marks: traditional signature marks are characters (letters/numbers) printed on the first page of each section and have to be read one by one. A Flattermark is a position-coded bar, and a misplaced section shows up at a glance as a break in the diagonal across the spine ⁸¹⁰. Signature marks have largely fallen out of use, while collation marks are still generated by current imposition software ¹⁰¹¹.
• Flattermarken vs. FIM: Zint's manual puts both in the same chapter, "Other Barcode-Like Markings" (§6.7.1 FIM, §6.7.2 Flattermarken). Both are fixed marks whose meaning depends on where they sit on the item rather than on general-purpose symbol data ¹. FIM uses a small set of fixed patterns, while Flattermarken take arbitrary digit strings ¹.

Fun facts

• Zint's source code introduces the encoder with the comment "Flattermarken - Not really a barcode symbology!", and still notes that it has no documentation for the mark's dimensions ².
• The German name comes from bookbinding vocabulary. Duden lists Flattermarke as a printing-trade term for a mark on the spine of every folded sheet "whose position changes uniformly" ⁷.

Status

Active as a print-production practice, niche as a barcode symbology. Collation marks are still a standard feature of current imposition software (KODAK Preps 11) ¹¹. The digit-encoding symbology is maintained in Zint (commits in 2026) and bwip-js (4.11.x) ¹²³. No standards body has published a formal specification. The implementations disagree on maximum length, and Zint's source admits that no dimension documentation exists ²³. No successor exists.

Sources

1 Zint Barcode Generator and Zint Barcode Studio User Manual (§6.7.2 Flattermarken; symbology table) — Robin Stuart / zint project, accessed 2026. 2 zint backend/postal.c — zint_flat() — GitHub (zint/zint), accessed 2026. 3 bwip-js — Barcode Writer in Pure JavaScript (README symbology list via jsDelivr; bwipp_flattermarken source in npm package 4.11.0) — metafloor, accessed 2026. 4 Flattermarken — DataFlex Reports documentation, accessed 2026. 5 Other Barcode-Like Markings — symbology.dev, accessed 2026. 6 Flattermarke — Wikipedia (German), accessed 2026. 7 Flattermarke — Duden, accessed 2026. 8 Black step — Bookbinding and the Conservation of Books: A Dictionary of Descriptive Terminology — Etherington & Roberts, via CoOL / AIC, accessed 2026. 9 Module: Collating Marks (README) — CTAN mirror, W. Egger, accessed 2026. 10 Signature mark — Wikipedia, accessed 2026. 11 Collation marks — KODAK Preps 11 — Kodak Workflow Help, accessed 2026. 12 Collation mark — Reconnaissance International glossary, accessed 2026.

Deployments

No country reports mention this standard by name.

Regions / aggregations not mapped to a single country

• Universal