HeaderDoc is a set of tools for embedding structured comments in source code and header files written in various languages and subsequently producing rich HTML and XML output from those comments. HeaderDoc comments are similar in appearance to JavaDoc comments in a Java source file, but traditional HeaderDoc comments provide a slightly more formal tag set to allow greater control over HeaderDoc behavior.

HeaderDoc is primarily intended for use on OS X, as part of the OS X Developer Tools. However, in various versions, it has also been used successfully on other operating systems, including Linux, Solaris, and Mac OS 9. (Your mileage may vary.)

In addition to traditional HeaderDoc markup, HeaderDoc 8 supports JavaDoc markup. HeaderDoc 8 supports a wide range of languages:

AppleScript
Bourne shell (and Korn and Bourne Again)
C Headers and C source code
C++ headers
C shell scripts
Java
JavaScript
Mach MIG definitions
Objective C/C++ headers
Pascal
Perl
Python
PHP
Ruby
Tcl