25.11 TeX Mode

Emacs provides special major modes for editing files written in TeX and its related formats. TeX is a powerful text formatter written by Donald Knuth; like GNU Emacs, it is free software. LaTeX is a simplified input format for TeX, implemented using TeX macros. DocTeX is a special file format in which the LaTeX sources are written, combining sources with documentation. SliTeX is an obsolete special form of LaTeX.¹¹

TeX mode has four variants: Plain TeX mode, LaTeX mode, DocTeX mode, and SliTeX mode. These distinct major modes differ only slightly, and are designed for editing the four different formats. Emacs selects the appropriate mode by looking at the contents of the buffer. (This is done by the tex-mode command, which is normally called automatically when you visit a TeX-like file. See Choosing Modes.) If the contents are insufficient to determine this, Emacs chooses the mode specified by the variable tex-default-mode; its default value is latex-mode. If Emacs does not guess right, you can select the correct variant of TeX mode using the command M-x plain-tex-mode, M-x latex-mode, M-x slitex-mode, or doctex-mode.

The following sections document the features of TeX mode and its variants. There are several other TeX-related Emacs packages, which are not documented in this manual:

• BibTeX mode is a major mode for BibTeX files, which are commonly used for keeping bibliographic references for LaTeX documents. For more information, see the documentation string for the command bibtex-mode.
• The RefTeX package provides a minor mode which can be used with LaTeX mode to manage bibliographic references. For more information, see the RefTeX Info manual, which is distributed with Emacs.
• The AUCTeX package provides more advanced features for editing TeX and its related formats, including the ability to preview TeX equations within Emacs buffers. Unlike BibTeX mode and the RefTeX package, AUCTeX is not distributed with Emacs by default. It can be downloaded via the Package Menu (see Packages); once installed, see the AUCTeX manual, which is included with the package.