This is a part of the [struct] module in the [tcllib] distribution.
     
The doc for this command will joyfully be found at
http://core.tcl.tk/tcllib/doc/trunk/embedded/www/tcllib/files/modules/struct/graph.html

Use this to create and manipulate directed graph objects.

[[anyone have examples of when to use this?]]

The companion package [struct::graphop] provides a number of graph algorithms.

<<categories>> Data Structure | Tcllib | Package | Graph Theory