One of the following DocBook elements: note, important, caution, warning, or tip.

alt text

Brief text associated with an image, to be displayed when the image cannot be displayed. Often stored in the ALT attribute of an HTML img element.

ancestor element

In an XML element hierarchy, any element that contains the current element, with any number of intervening containers.

aspect ratio

The ratio of width to height of an image.

attribute set

A collection of attribute names and values that can be assigned a name and used as a group. See the section “Attribute sets” for more information.

body font

The font used for the ordinary text of a document.


Explanatory text associated with a particular part of an image or text display. Often labeled with callout bugs on the image and explanation. See the section “Callouts” for more information.

callout bug

Graphical or numeric marker used to key a particular callout explanation to its associated location in an image or text display.

CALS table

An SGML standard for table element names and structure developed by the U.S. military. The CALS table tags were adopted for use in DocBook.


A file that provides a mapping of identifiers to actual file locations to be used in the current process. The identifiers could be PUBLIC or SYSTEM identifiers for DTDs or system entities, as well as URIs for stylesheet files. The file locations being mapped to can be local directory paths or URIs. See Chapter 5, XML catalogs for more information.


Text that is meant to be interpreted as containing no XML markup. All characters are taken literally, which means the < character is not interpreted to indicate the start of an XML element, and the & character is not interpreted as the start of an entity reference.

character entity

An entity that represents a single character. A character entity can be expressed with a name such as &trade;, as a decimal number such as &#234;, or as a hexadecimal number such as &#x2344;.

child element

An element contained by the current element, with no intervening containers.


The process of generating multiple HTML files (chunks) from a single DocBook document. See the section “Chunking into multiple HTML files” for more information.


In DocBook, a class of elements that make up the parts of a book. The class includes chapter, appendix, preface, dedication, colophon, article, bibliography, glossary, and index.


Cascading Stylesheets, a W3C standard for HTML stylesheets.

customization layer

An XSL stylesheet that layers customization changes on top of the existing DocBook XSL templates, without altering the original stylesheet files. See the section “Customization layer” for more information.

descendant element

In an XML element hierarchy, any element that is contained by the current element, with any number of intervening containers.


In DocBook, a class of elements that make up the highest levels of document hierarchy. The class includes set, book, part, and reference.


A declaration at the start of an XML document that identifies the document's root element and DTD.


In DocBook, a well-formed or valid XML document, with a single root element that contains the document's content.


Document Type Definition, which declares a set of XML element names and how they can be used in a document.


A mapping of numerical codes to visible character glyphs. Examples include UTF-8 and ISO-8859-1 among many others. See the section “Document encoding” for more information.


A declaration that maps a name to some specific bit of information in XML. There are several kinds of entities: character entities, general entities, parameter entities, and system entities. An entity must be declared before it can be referenced.

entity reference

The usage of an entity in a document or DTD. An entity reference consists of an ampersand, followed by an entity name, followed by a semicolon, such as &trade; for example.


A community initiative to provide extensions to XSLT.

external subset

The parts of a DTD defined in a separate file that is referenced by the PUBLIC and SYSTEM identifiers in a document's DOCTYPE declaration.


An object such as a graphic or table that can float out of the normal flow of text to a new position on a printed page.


Formatting Objects, the part of the XSL standard used for specifying typesetting instructions. Also known as XSL-FO.

FO processor

See XSL-FO processor.


In DocBook, the text or graphics that appears at the bottom of a printed page or HTML page.


In DocBook, a class of display elements that contain a title and is usually numbered. The class includes figure, table, example, and equation.

fragment identifier

That part of a URL that appears after the # symbol. It points to an internal location within the resource.

general entity

An entity that can contain ordinary text, elements, and entity references. Often used to define commonly used strings.


In DocBook, the system for generating text not present in the document, such as Chapter 3 or Table of Contents. The gentext system supports multiple languages. See the section “Generated text” for more information.


A displayable character.

hanging indent

A format style that puts a small amount of text hanging out in the left margin, while the main body is indented to make room for it. Used primarily for variablelist elements.


In DocBook, the text or graphics that appears at the top of a printed page or HTML page.


An abbreviation of the word internationalization (i, followed by 18 letters, followed by n).


In DocBook, the attribute that is used as a unique identifier of an element, for the purpose of cross referencing. This attribute value may also play a role in generating chunked HTML filenames.

import precedence

In XSL, the rules governing which of several candidate templates, from the current stylesheet and any imported stylesheets, that could apply is actually used.


In DocBook, a class of display elements that do not have a title and are not numbered. The class includes informaltable, informalfigure, informalexample, and informalequation.

inline element

A DocBook element that can appear within a line of text. An example is an emphasis element used within the text of a para.

internal subset

The parts of a DTD declared within the DOCTYPE declaration at the beginning of an XML document. The rest of the DTD is declared in the external subset of the DTD, which is the DTD file referenced by the PUBLIC and SYSTEM identifiers in the DOCTYPE.


The process of enabling software to work with multiple languages. It does not necessarily include translation to multiple languages, it just enables such translations.


An abbreviation for the word localization (the letter L, followed by ten letters, followed by n).


A condition added to an XSL-FO file to keep elements together on a page. A keep-together condition keeps all of an element's children together on a page. A keep-with-next keeps the current element with the following element, and a keep-with-previous keeps the current element with the preceding element.


In DocBook, the number associated with a numbered item like a chapter or table. Also sometimes refers to the text associated with the number as well, such as Chapter 3.


The process of translating software into another language. This includes translating text, as well as handling the formatting of information such as dates and currency.


An element in DocBook used to contain several imageobject elements, only one of which is used for a given output. See Chapter 18, Graphics for more information.


In DocBook, the splitting of large documents into several smaller document files. Each modular file can be treated as a small document, and they can be merged back together to form larger documents. See Chapter 23, Modular DocBook files for more information.


In XML, the means to support elements from different DTDs in the same document. The set of elements from each DTD is said to occupy its own namespace. An element in a given namespace can be identified by assigning a namespace prefix that is attached to element names, as for example fo:inline.

namespace name

The URI that identifies a namespace uniquely. For example, There is no requirement that any content actually reside at that URI's network address.

namespace prefix

A text string assigned as an element name prefix to a namespace. When an element name is preceded by the prefix and a colon, then that element is in that assigned namespace.


Organization for the Advancement of Structured Information Standards, responsible for the development and maintenance of the DocBook DTD.

output encoding

The name of the character encoding used for output files generated by the stylesheet. Examples include utf-8 and iso-8859-1.

See Also encoding.

page class

In the DocBook print stylesheets, the name of any of several kinds of page designs. The supported page class names include titlepage, lot, front, body, back, and index.

page master

In XSL-FO, the specifications for a single design for a page. Typically a page class will have four page masters for first, odd, even, and blank pages used within the class.


In XSL, a named value that affects the behavior of the processing. DocBook XSL defines dozens of stylesheet parameters, which can be reset to different values from the command line or a customization layer.

parameter entity

An entity used exclusively within a DTD, never in a document.

parent element

The element containing the current element, with no intervening container elements.


Ordinary text without any XML element tags.


Portable Document Format, a file format for electronic documents that can be printed with accurate page fidelity.


Abbreviation for processing instruction.


In DocBook XSL, a defined but empty template. Such templates can be redefined in a customization layer, and they are called or applied automatically at the appropriate time.

processing instruction

An XML construct that can be used to embed hidden instructions in a document. Such instructions can provide information to a processor to affect the processor behavior or to apply formatting that cannot be specified with elements or attribute values.


The act of selecting conditional text in a document to create a version for a given user profile. See Chapter 26, Profiling (conditional text) for more information.

PUBLIC identifier

A unique identifier for a DTD or system entity. It adheres to the standard for PUBLIC identifier syntax and is usually resolved using a catalog.


The front side of a double-sided printed page. Appears on the right side of an open bound book.

root element

In an XML document, the single element that contains all the content of the document.

run-in title

A title that appears as the first part of a paragraph, with the text of the paragraph starting after the title but on the same line as the title.


Standard Generalized Markup Language, the predecessor to XML.

side float

A block of content that is positioned out of line to the side of the printed page.

soft page break

A processing instruction that creates a conditional page break. If the conditions are not satisfied, then the page does not break. This differs from a hard page break, which is not conditional.


Website that contains many open source projects, including the DocBook XSL stylesheets.

stylesheet parameter

See parameter.

stylesheet module

A file containing some XSL templates and/or parameters. An XSL stylesheet can be split among several files, and assembled using xsl:include and xsl:import. Each file is a module of the entire stylesheet.


Scalable Vector Graphic, a graphic file format written in XML for images that scale smoothly to different sizes. See the section “SVG images” for more information.

system entity

An entity that identifies another file that is to be included when the entity is referenced.

SYSTEM identifier

A URI address for locating a DTD or system identifier.

target database

A database of id-related information collected from documents. The information can be used to form cross references between documents using olink. See Chapter 24, Olinking between documents for more information.


In DocBook XSL, there are three distinct kinds of templates: XSL, gentext, and titlepage templates. XSLT templates perform the main transformation of content.

Gentext templates define generated text produced by the stylesheets.

Titlepage templates define what information appears on title pages, and in what order.


Open-source typesetting system, used in the PassiveTeX FO processor.

text entity

See general entity.

title page

In DocBook, the subsystem that handles the title and other info elements at the beginning of a division or component. In many cases, a title page is not a separate page.


Table of contents.


International encoding standard that provides a superset of many separate encodings.


One of the optional encodings of Unicode. Uses a variable number of bytes in the encoding for different character ranges.


Process that determines if an XML document conforms to its DTD.

vector graphic

Graphical image based on a mathematical specification of geometric elements. Vector graphics scale cleanly to any size.


The back side of a double-sided printed page. Appears on the left side of an open bound book.


The space in a document presentation that is reserved for an image. The viewport can be larger than the image, leaving extra space around it. Or it can be smaller than the image, clipping the edges. See the section “ Image sizing” for more information.


Worldwide Web Consortium, which develops industry standards for XML and other areas.


In DocBook, the extension of DocBook that can generate a set of HTML pages that make up a website. See Chapter 31, Website for more information.


An XML document that follows all the rules of XML, but has not necessarily been validated against a DTD.


A reformulation of HTML to conform to the XML specification.


A processing model and syntax for including content from other sources in an XML document. See the section “Using XInclude” for more information.


A W3C standard for forming links between XML documents.


A language for addressing parts of an XML document, designed to be used by XSLT.


Extensible Stylesheet Language, a language for expressing stylesheets in XML syntax. Includes XSLT and XSL-FO.


XSL Transformation, a language for transforming XML documents into other XML documents, HTML, or text.

XSLT processor

Software component that applies an XSL stylesheet to an XML document to produce output in the form of XML, HTML, or text.


XSL Formatting Objects, a language for expressing formatting semantics using an XML vocabulary.

XSL-FO processor

Software component that converts an XSL-FO document into a formatted document.