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Chapter Structuring

The chapter structuring commands divide a document into a hierarchy of chapters, sections, subsections, and subsubsections. These commands generate large headings; they also provide information for the table of contents of a printed manual (see section Generating a Table of Contents).

The chapter structuring commands do not create an Info node structure, so normally you should put an @node command immediately before each chapter structuring command (see section Nodes). The only time you are likely to use the chapter structuring commands without using the node structuring commands is if you are writing a document that contains no cross references and will never be transformed into Info format.

It is unlikely that you will ever write a Texinfo file that is intended only as an Info file and not as a printable document. If you do, you might still use chapter structuring commands to create a heading at the top of each node--but you don't need to.

Tree Structure of Sections

A Texinfo file is usually structured like a book with chapters, sections, subsections, and the like. This structure can be visualized as a tree (or rather as an upside-down tree) with the root at the top and the levels corresponding to chapters, sections, subsection, and subsubsections.

Here is a diagram that shows a Texinfo file with three chapters, each of which has two sections.

                          Top
                           |
         -------------------------------------
        |                  |                  |
     Chapter 1          Chapter 2          Chapter 3
        |                  |                  |
     --------           --------           --------
    |        |         |        |         |        |         
 Section  Section   Section  Section   Section  Section
   1.1      1.2       2.1      2.2       3.1      3.2

In a Texinfo file that has this structure, the beginning of Chapter 2 looks like this:

@node    Chapter 2,  Chapter 3, Chapter 1, top
@chapter Chapter 2

The chapter structuring commands are described in the sections that follow; the @node and @menu commands are described in following chapters. (See section Nodes, and see section Menus.)

Types of Structuring Command

The chapter structuring commands fall into four groups or series, each of which contains structuring commands corresponding to the hierarchical levels of chapters, sections, subsections, and subsubsections.

The four groups are the @chapter series, the @unnumbered series, the @appendix series, and the @heading series.

Each command produces titles that have a different appearance on the printed page or Info file; only some of the commands produce titles that are listed in the table of contents of a printed book or manual.

The @chapter and @appendix series of commands produce numbered or lettered entries both in the body of a printed work and in its table of contents.
The @unnumbered series of commands produce unnumbered entries both in the body of a printed work and in its table of contents. The @top command, which has a special use, is a member of this series (see section @top).
The @heading series of commands produce unnumbered headings that do not appear in a table of contents. The heading commands never start a new page.
The @majorheading command produces results similar to using the @chapheading command but generates a larger vertical whitespace before the heading.
When an @setchapternewpage command says to do so, the @chapter, @unnumbered, and @appendix commands start new pages in the printed manual; the @heading commands do not.

Here are the four groups of chapter structuring commands:

`@top`

The @top command is a special sectioning command that you use only after an @node Top line at the beginning of a Texinfo file. The @top command tells the makeinfo formatter which node is the `Top' node. It has the same typesetting effect as @unnumbered (see section @unnumbered, @appendix). For detailed information, see section The @top Sectioning Command.

`@chapter`

@chapter identifies a chapter in the document. Write the command at the beginning of a line and follow it on the same line by the title of the chapter.

For example, this chapter in this manual is entitled "Chapter Structuring"; the @chapter line looks like this:

@chapter Chapter Structuring

In TeX, the @chapter command creates a chapter in the document, specifying the chapter title. The chapter is numbered automatically.

In Info, the @chapter command causes the title to appear on a line by itself, with a line of asterisks inserted underneath. Thus, in Info, the above example produces the following output:

Chapter Structuring
*******************

`@unnumbered`, `@appendix`

Use the @unnumbered command to create a chapter that appears in a printed manual without chapter numbers of any kind. Use the @appendix command to create an appendix in a printed manual that is labelled by letter instead of by number.

For Info file output, the @unnumbered and @appendix commands are equivalent to @chapter: the title is printed on a line by itself with a line of asterisks underneath. (See section @chapter}.)

To create an appendix or an unnumbered chapter, write an @appendix or @unnumbered command at the beginning of a line and follow it on the same line by the title, as you would if you were creating a chapter.

`@majorheading`, `@chapheading`

The @majorheading and @chapheading commands put chapter-like headings in the body of a document.

However, neither command causes TeX to produce a numbered heading or an entry in the table of contents; and neither command causes TeX to start a new page in a printed manual.

In TeX, an @majorheading command generates a larger vertical whitespace before the heading than an @chapheading command but is otherwise the same.

In Info, the @majorheading and @chapheading commands are equivalent to @chapter: the title is printed on a line by itself with a line of asterisks underneath. (See section @chapter.)

`@section`

In a printed manual, an @section command identifies a numbered section within a chapter. The section title appears in the table of contents. In Info, an @section command provides a title for a segment of text, underlined with `='.

This section is headed with an @section command and looks like this in the Texinfo file:

@section @code{@@section}

To create a section, write the @section command at the beginning of a line and follow it on the same line by the section title.

Thus,

@section This is a section

produces

This is a section
=================

in Info.

`@unnumberedsec`, `@appendixsec`, `@heading`

The @unnumberedsec, @appendixsec, and @heading commands are, respectively, the unnumbered, appendix-like, and heading-like equivalents of the @section command. (See section @section.)

@unnumberedsec

The @unnumberedsec command may be used within an unnumbered chapter or within a regular chapter or appendix to provide an unnumbered section.

@appendixsec

@appendixsection

@appendixsection is a longer spelling of the @appendixsec command; the two are synonymous.

Conventionally, the @appendixsec or @appendixsection command is used only within appendices.

@heading

You may use the @heading command anywhere you wish for a section-style heading that will not appear in the table of contents.

The `@subsection` Command

Subsections are to sections as sections are to chapters. (See section @section.) In Info, subsection titles are underlined with `-'. For example,

@subsection This is a subsection

produces

This is a subsection
--------------------

In a printed manual, subsections are listed in the table of contents and are numbered three levels deep.

The `@subsection`-like Commands

The @unnumberedsubsec, @appendixsubsec, and @subheading commands are, respectively, the unnumbered, appendix-like, and heading-like equivalents of the @subsection command. (See section The @subsection Command.)

In Info, the @subsection-like commands generate a title underlined with hyphens. In a printed manual, an @subheading command produces a heading like that of a subsection except that it is not numbered and does not appear in the table of contents. Similarly, an @unnumberedsubsec command produces an unnumbered heading like that of a subsection and an @appendixsubsec command produces a subsection-like heading labelled with a letter and numbers; both of these commands produce headings that appear in the table of contents.

The `subsub' Commands

The fourth and lowest level sectioning commands in Texinfo are the `subsub' commands. They are:

@subsubsection: Subsubsections are to subsections as subsections are to sections. (See section The @subsection Command.) In a printed manual, subsubsection titles appear in the table of contents and are numbered four levels deep.
@unnumberedsubsubsec: Unnumbered subsubsection titles appear in the table of contents of a printed manual, but lack numbers. Otherwise, unnumbered subsubsections are the same as subsubsections. In Info, unnumbered subsubsections look exactly like ordinary subsubsections.
@appendixsubsubsec: Conventionally, appendix commands are used only for appendices and are lettered and numbered appropriately in a printed manual. They also appear in the table of contents. In Info, appendix subsubsections look exactly like ordinary subsubsections.
@subsubheading: The @subsubheading command may be used anywhere that you need a small heading that will not appear in the table of contents. In Info, subsubheadings look exactly like ordinary subsubsection headings.

In Info, `subsub' titles are underlined with periods. For example,

@subsubsection This is a subsubsection

produces

This is a subsubsection
.......................

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