GLOBAL is a source code tag system that works the same way across
diverse environments. Currently, it supports the following:

    Shell command line
    nvi editor
    Web browser
    emacs editor
    elvis editor

Supported languages are C, Yacc and Java.  You can locate a specified
function in the source files and move there easily.  It is useful for
hacking a large project containing many subdirectories, many '#ifdef'
and many main() functions, like MH, X or BSD kernel.  GLOBAL consists
of global(1), gtags(1), btreeop(1), gctags(1), htags(1), extended
vi(1), gtags.el and gozilla(1).