12.1 Introduction

Nroff and troff are UNIX programs for formatting text files. Nroff is designed to format output for line printers and letter-quality printers; you can also display the output on your screen. Troff is designed for typesetting. Except for some functions that are specific to typesetting, the same commands work for both programs.

Nroff and troff are not part of standard SVR4 but are included in the compatibility packages. It is this version that is documented here. Note, however, that some UNIX distributors include a vendor-specific version of nroff/troff. Various enhanced packages are also available, such as sqtroff from SoftQuad or groff from the Free Software Foundation. These packages might include additional requests or escape sequences. For completely accurate information, we recommend that you consult the text processing manuals that come with your specific UNIX implementation.

In addition, we make references to ditroff, or device-independent troff, which is a later version of troff. For the most part, ditroff works the same as troff; where there are distinctions, the original troff is referred to as otroff.