troff reads text files (written using an instream formatting language, see [nroff]) and formats the text for typesetting or laser printing.

The most common modern implementation is [GNU] [groff].

The connection to Tcl is that the Tcl [man] pages - the only documentation that comes with the source - uses the *roff markup formatting language.

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**Simple Tutorial on Writing a Tcl Manpage**
Firstly, always remember to look at other manual pages to see what sort of things belong!

***The Header***
Tcl manual pages start with:
===
 .so man.macros
 .TH ''name'' ''section'' ''version'' Tcl "Tcl Built-In Commands"
 .BS
 .SH NAME
 ''names'' \- ''description''
 .SH SYNOPSIS
 .nf
 ''summary of commands/functions''
 .fi
 .BE
===

The ''name'' is the name of the manual page.
The ''section'' is (typically) '''n''' for commands (e.g. [lsearch]), '''3''' for [C] API functions (e.g. [Tcl_SetObjResult]), or '''1''' for programs/shells (e.g. [tclsh]).
The ''version'' is the version of Tcl/extension where the page last had substantive changes.
The ''names'' is a comma-separated list of all the commands or functions documented on the page, and must (along with the ''description'') be on a single line.
The ''description'' is a very short description of what the commands/functions do (e.g. [lsearch]s' page says "See if a list contains a particular element"), and must be on a single line (along with the ''names'').
The ''summary of commands/functions'' is what it says; check some examples for how to write them.

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!!!!!!
%| [Category Word and Text Processing] |%
!!!!!!