Glossary

Typesetting and the page

Back matter

The pages after the main text: appendices, notes, glossary, bibliography, index.

Back-of-book index

The alphabetical list of subjects at the end of a book, each with the pages where it appears.

Badness and demerits

The scores Knuth–Plass gives a line: badness grows with how far its spaces are stretched or squeezed, and demerits add the cost of hyphens and of uneven neighbouring lines. The paragraph with the lowest total wins.

Baseline

The invisible line letters sit on. Descenders such as the tail of p go below it.

Baseline grid

A set of equally spaced horizontal lines that every line of body text sits on, so lines in neighbouring columns and on facing pages line up.

Bleed

Artwork that runs past the trim edge, a few millimetres beyond the page, so no white line shows if the cut is slightly off.

Boxes, glue and penalties

The model Knuth–Plass works on. Boxes are words or letters of fixed width, glue is space that can stretch or shrink, and penalties mark places where a break is allowed at a cost, such as a hyphen.

Byline

The line that names the author of an article or a chapter in a collection.

Callout

A boxed passage set apart from the running text, such as a note, a warning or a sidebar. Postext writes them with the :::callout directive.

Caption

The text that labels a figure or table, usually with its number: Figure 3, Table 2.

Colophon

A short note, usually at the end of a book, on how it was made: the typefaces, the paper, the printer.

Column balancing

Making the columns of a page end at the same height, typically on the last page of a chapter, by moving lines between them or adjusting spacing.

Crop marks

Thin lines printed outside the page corners that show the printer where to cut.

Cross-reference

A mention of another place in the same book, such as “see Figure 4” or “page 12”, that stays correct when the layout changes.

Drop cap

A large initial letter at the start of a paragraph that sinks several lines into the text beside it.

Em

A unit equal to the type size: in 10 pt type, an em is 10 pt. Spacing in typesetting is often given in ems or fractions of an em.

En

Half an em. The en dash (–) is about this wide.

En dash and em dash

The en dash (–) joins ranges, as in 1914–1918; the em dash (—) sets off a phrase in English. Neither is a hyphen.

Epigraph

A short quotation placed at the start of a book or chapter, with its source.

Float

A figure, table or box that the layout may move away from its place in the text, to the top or bottom of a column or page, where it fits.

Folio

The printed page number. A drop folio sits at the foot of the page.

Footnote

A note printed at the foot of the column or page where it is cited, linked to the text by a superscript number or mark.

Front matter

The pages before the main text: title page, copyright page, dedication, contents, preface. They are often numbered in roman numerals.

Gloss

A short explanation of a word or line, printed in the margin, between the lines or in notes, as in annotated classics.

Glyph

One drawn shape in a font. A letter may have several glyphs (a ligature, a small cap, a vertical form).

Greedy line breaking

Filling each line with as many words as fit before moving to the next, without looking ahead. It is what CSS does, and it leaves some lines much looser than others.

Gutter

The space between two columns of text. Some printers also call the inner margin by the spine the gutter.

Hyphenation

Dividing a word at the end of a line, with a hyphen, at a point the language allows. Postext finds those points with TeX's patterns for each language.

Justification

Setting text so every full line reaches both the left and the right edge of the column, by adjusting the space inside the line.

Keep together

A rule that a block, such as a heading with its first lines or a short box, must not be split across columns or pages.

Kerning

A space adjustment between two particular letters, such as A and V, so the pair looks evenly spaced. The font carries the values.

Kicker

A short line set above a heading, such as “Chapter 3” or a section name, in smaller or spaced capitals.

Knuth–Plass algorithm

The line-breaking method of the TeX typesetting system. It weighs every possible set of breaks in a paragraph and picks the one with the most even spacing, where a browser fills one line at a time.

Leading

The distance from one baseline to the next. The word comes from the strips of lead that compositors laid between lines of metal type.

Ligature

Two or more letters drawn as one glyph, such as fi or ff, to avoid awkward collisions.

Measure

The length of a line of text, the width of the column. Comfortable reading needs roughly 45 to 75 characters.

Mirrored margins

Margins that swap sides between left and right pages, so the inner margin is always by the spine.

Opener

The designed first page of a chapter or part, with its number, title and often a band of colour or an image.

Orphan

In Postext, the last line or lines of a paragraph carried alone to the top of the next column or page. Typographers disagree on the name; the rule is about lines stranded by a column break.

Point and pica

Typographic units. A point is 1/72 of an inch (about 0.35 mm); a pica is 12 points.

Pull quote

A sentence from the text repeated in large type inside the page to catch the eye, common in magazines.

Ragged right

Text aligned on the left only, with lines of uneven length on the right. Word spacing stays constant.

Recto

The right-hand page of an open book in left-to-right binding, always odd-numbered. Chapters traditionally open on a recto.

Rule

A printed line, such as the thin line between columns or under a running head.

Running head

A line repeated at the top of each page, usually the book or chapter title, to tell the reader where they are.

Runt

A paragraph's last line when it holds only a word or part of one. Postext penalises it and, when it can, sets the paragraph one line shorter.

Signature

A large sheet printed with several pages and folded into a gathering, such as 16 pages. Books are sewn signature by signature.

Small caps

Capital letters drawn at about the height of lowercase letters, used for abbreviations and running heads so they do not shout.

Soft hyphen

An invisible mark inside a word that shows where it may be divided. It prints as a hyphen only when the line actually breaks there.

Spot colour and single ink

A spot colour is one premixed ink printed on its own. A single-ink book prints everything in one such ink, with lighter tints for greys.

Spread

Two facing pages seen together, a verso and a recto. Designers plan a book spread by spread.

Swatch

A named colour in a design's palette, reused by headings, rules and boxes so a change in one place reaches them all.

Tracking

Extra space added or removed between every letter of a line or a word. Postext measures it in thousandths of an em and uses it sparingly, after word spacing.

Trim size

The final size of a printed page after it is cut, such as 140 × 210 mm.

Type area

The part of the page that holds the text, inside the margins. Running heads and folios usually sit outside it.

Typeface and font

A typeface is the design (Garamond); a font is one file or style of it (Garamond Italic).

Verso

The left-hand page of an open book in left-to-right binding, always even-numbered. In a book bound on the right, as many vertical Chinese books are, the sides swap.

Widow

In Postext, the first line or lines of a paragraph left alone at the bottom of a column or page, with the rest of the paragraph overleaf.

Word spacing

The width of the spaces between words. A justified line stretches or shrinks them within limits set in the configuration.

Chinese layout

Book-title mark书名号

The marks that set off the title of a book or article: 《》 in modern mainland text, or a wavy line under it in classical and Taiwanese editions.

Character grid字格

The Chinese way to specify a type area: so many characters per line and so many lines per page, every character on a square cell.

Chinese point sizes字号

Named type sizes used in China: 五号 is 10.5 pt, the usual book size; 小五 is 9 pt; 四号 is 14 pt.

clreq中文排版需求

Requirements for Chinese Text Layout, the W3C document that describes how Chinese text is set. The Postext docs cite it by section.

Emphasis dots着重号

Dots set under each character (beside it in vertical text) to stress a phrase. Chinese uses them where Latin text uses italics.

Fore-edge heads书口

In vertical books, the chapter title and folio set down the outer margin of the page rather than across its top.

Full-width全角

Occupying a whole em cell, like a Han character. Chinese punctuation and full-width digits (１２) are full-width; Latin letters are not.

Han characters汉字

The Chinese characters (hanzi), also used in Japanese and, historically, Korean. Each takes a square cell one em wide.

Han–Latin spacing中西文间距

A quarter-em gap set between a Han character and a Latin letter or digit next to it, as in 1999 年.

Hanging punctuation标点悬挂

Letting a comma or full stop that does not fit sit just past the end of the line instead of pushing a character down.

Ideographic space全角空格

A blank one em wide (U+3000), the width of a Han character, used for indents and after chapter numbers.

Kaiming style开明式

A punctuation style that sets pause marks (、，) half-width and stops (。) full-width, a compromise between full-width and half-width setting.

Line-start and line-end rules避头尾

The rules that keep certain marks off the start of a line (a comma, a closing bracket) and others off the end (an opening bracket). Japanese calls them kinsoku.

Pinyin拼音

The official romanisation of Mandarin, with tone marks: hóng lóu.

Proper-name mark专名号

A straight line under a personal or place name (beside it in vertical text), found in classical and Taiwanese editions.

Punctuation width and compression标点挤压

A Chinese mark is half an em of glyph and half an em of blank. Compression removes some of that blank, for example where two marks meet, so 。」 takes one and a half ems instead of two.

Right binding右装

A book bound on its right edge, opened from what a Western reader thinks of as the back. Vertical Chinese books are bound this way.

Ruby注音

Small text set above or beside characters to give their reading, such as pinyin or zhuyin.

Tate-chu-yoko纵中横

Setting a short number or acronym across the column, upright in a single cell, inside vertical text. The name is Japanese for “horizontal in vertical”.

Tier栏

In vertical writing, one of the horizontal bands a page is divided into, the vertical counterpart of a column.

Vertical writing竖排

Text set in columns that run from top to bottom, read from right to left, as in many Taiwanese and classical Chinese books.

Warichu双行夹注

A note set in two half-size rows inside the line, the form of commentary in classical Chinese editions. The name is Japanese.

Zhuyin (bopomofo)注音符号

A phonetic alphabet for Mandarin used in Taiwan (ㄅㄆㄇㄈ), set in a column beside each character.

Software and the web

Alternative text

A short description of an image for people who cannot see it, read aloud by screen readers.

Bundle (.postext)

A single file that packs a book's chapters, configuration, fonts and images, so it opens the same anywhere.

Canvas

The HTML element a web page draws pixels on with JavaScript. The Sandbox previews pages on it.

Directive

Postext's extension to Markdown for things Markdown lacks, written with colons: :::callout for a box, :ref[…] for a cross-reference.

Font subset

A copy of a font that keeps only the characters a document uses, so the file is smaller. PDFs embed subsets.

Frontmatter

A block of settings at the top of a file, between two lines of ---, such as the title and author of a chapter. Not the same as a book's front matter.

Headless

Running without a visible window, for example generating PDFs on a server or in a script.

IndexedDB

A database built into the browser. The Sandbox keeps your books and drafts in it, on your own device.

Markdown

A plain-text way to write formatted text: # for headings, * for emphasis, - for lists. Postext reads book chapters written in it.

OpenType

The standard font format, which can hold features such as ligatures, small caps and vertical punctuation forms.

Preset

A ready-made book in the Sandbox, with its design and sample text, to start from or study.

Renderer

The part that draws the laid-out pages in one output: canvas, HTML or PDF. The layout is the same for all three.

Sandbox

Postext's editor in the browser: write a book, change its design and see the pages update.

Tagged PDF

A PDF that carries a structure tree of headings, paragraphs, lists and figures with alternative text, so screen readers can read it in order.

Variable font

One font file that holds a range of weights or widths, picked by a number instead of a separate file for each.

Vector and raster

A vector image is drawn from shapes and stays sharp at any size (SVG); a raster image is a grid of pixels (PNG, JPEG).

Virtual Document Tree

Postext's laid-out book: every page, line and glyph with its position, ready for a renderer to draw.

Web Worker

A script the browser runs in the background, apart from the page, so long work such as laying out a book does not freeze the interface.

WebAssembly (WASM)

A compact binary format browsers run at near-native speed, used by libraries that need heavy computation, such as font decompression.

Abbreviations

On docs and recipe pages the first use of each one is marked, and its expansion appears when you point at it. This list covers the rest of the site.

APA

American Psychological Association (a citation style)

API

application programming interface

ASCII

American Standard Code for Information Interchange

AST

abstract syntax tree

BCP

Best Current Practice (BCP 47 defines language tags)

CDN

content delivery network

CFF

Compact Font Format

CJK

Chinese, Japanese and Korean

CLDR

Unicode Common Locale Data Repository

CLI

command-line interface

clreq

Requirements for Chinese Text Layout (W3C)

cm

centimetres

CMYK

cyan, magenta, yellow and black (key), the four process inks

CORS

cross-origin resource sharing

CSS

Cascading Style Sheets

CSV

comma-separated values

DIN

Deutsches Institut für Normung, the German standards body

DOCX

Word document (Office Open XML)

DOM

Document Object Model, the browser's tree of a page

DPI

dots per inch

e.g.

for example

EEA

European Environment Agency

EPUB

electronic publication, the standard e-book format

ESM

ECMAScript modules

GB/T

recommended national standard of China (Guobiao tuijian)

GDP

gross domestic product

GDPR

General Data Protection Regulation (EU)

GFM

GitHub Flavored Markdown

GIF

Graphics Interchange Format

GPU

graphics processing unit

HTML

HyperText Markup Language

HTTP

Hypertext Transfer Protocol

i.e.

that is

ICC

International Color Consortium (colour profiles)

IDML

InDesign Markup Language

ISBN

International Standard Book Number

JATS

Journal Article Tag Suite

JLREQ

Requirements for Japanese Text Layout (W3C)

JPEG

Joint Photographic Experts Group, the photo image format

JSON

JavaScript Object Notation

JSX

JavaScript XML, the tag syntax of React

KLREQ

Requirements for Hangul Text Layout (W3C)

KP

Knuth–Plass, the line-breaking algorithm

LLM

large language model

MDX

Markdown with JSX components

MIT

Massachusetts Institute of Technology, which wrote the MIT License

mm

millimetres

npm

the Node.js package registry and its command-line client

OCR

optical character recognition

ODT

OpenDocument text document

OFL

SIL Open Font License

OTF

OpenType font file

PDF

Portable Document Format

PDF/UA

PDF/Universal Accessibility, the ISO 14289 standard for accessible PDF

PDF/X

the ISO 15930 family of PDF standards for print exchange

PNG

Portable Network Graphics

PPTX

PowerPoint presentation (Office Open XML)

pt

points (1/72 inch)

px

CSS pixels

RAE

Real Academia Española

RGB

red, green and blue, the screen colour channels

ROC

Republic of China (Minguo calendar)

SSR

server-side rendering

SVG

Scalable Vector Graphics

TOC

table of contents

TSV

tab-separated values

TTF

TrueType font file

UAX

Unicode Standard Annex

UI

user interface

URI

Uniform Resource Identifier

URL

Uniform Resource Locator, a web address

UTC

Coordinated Universal Time

VDT

Virtual Document Tree, Postext's laid-out document

W3C

World Wide Web Consortium

WAI

Web Accessibility Initiative (W3C)

WCAG

Web Content Accessibility Guidelines

WOFF

Web Open Font Format

WOFF2

Web Open Font Format 2, compressed with Brotli

WYSIWYG

what you see is what you get

XMP

Extensible Metadata Platform

YAML

YAML Ain't Markup Language, a plain-text data format

ZIP

a compressed archive format