Documentation can be found at http://tcllib.sourceforge.net/doc/tree.html .
This module of the tcllib data structures collection provides the data structure portion of a tree structure.
Tree would be more useful if nodes could be arbitrary objects (specifically, if they could be incrTcl objects.) To that end, I made some mods which string map {:: @} in the creation of namespace data arrays. Worth adding to the mainline? CMCc
Category Command, package tcllib, module struct - Arts and Crafts of Tcl-Tk Programming