#### 25.1.1 `\addcontentsline`

Synopsis:

```\addcontentsline{ext}{unit}{text}
```

Add an entry to the file specified by ext. Usually ext is one of `toc` for the table of contents, `lof` for the list of figures, or `lot` for the list of tables.

```\addcontentsline{toc}{section}{\protect\textbf{Appendices}}
```

It will appear at the same indentation level as the sections, will be in boldface, and will be assigned the page number associated with the point where it appears in the input file.

The `\addcontentsline` command writes information to the file root-name.ext. It writes that information as the text of the command `\contentsline{unit}{text}{num}`, where `num` is the current value of counter `unit`. The most common case is the table of contents and there num is the page number of the first page of unit.

This command is invoked by the sectioning commands `\chapter`, etc., and also by `\caption` inside a float environment. But it is also used by authors. For example, in a book to have the preface unnumbered, you may use the starred `\chapter*`. But that does not put in table of contents information, so you can enter it manually, as here.

```\chapter*{Preface}
```

In the .toc file LaTeX will put the line ```\contentsline {chapter}{\numberline {}Preface}{3}```; note the page number ‘3’.

All of the arguments for `\addcontentsline` are required.

ext

Typically one of the strings `toc` for the table of contents, `lof` for the list of figures, or `lot` for the list of tables. The filename extension of the information file.

unit

A string that depends on the value of the ext argument:

`toc`

For the table of contents, this is the name of a sectional unit: `part`, `chapter`, `section`, `subsection`, etc.

`lof`

For the list of figures: `figure`.

`lot`

For the list of tables: `table`.

text

The text of the entry. You must `\protect` any commands that are fragile (see \protect).

The `\addcontentsline` command has an interaction with `\include` (see \include & \includeonly). If you use them at the same level, as with `\addcontentsline{...}{...}{...}\include{...}` then lines in the table of contents can come out in the wrong order. The solution is to move `\addcontentsline` into the file being included.

If you use a unit that LaTeX does not recognize, as here

```\addcontentsline{toc}{setcion}{\protect\textbf{Appendices}}
```

then you don’t get an error but the formatting in the table of contents will not make sense.