Tcl - tool command language
Tcl, the tool command language, is a simple scripting
language for controlling and extending applications.
It provides generic programming facilities such as variables,
loops, and procedures. Its key features are its ability to
be embedded within applications and its easy extensibility.
The Tcl programming language is described in detail in John K.
Ousterhout's Tcl and the Tk Toolkit
(Addison-Wesley, 1994). The widget toolkit supported
by the SCO implementation is not compatible with Tk,
and is described
later in this guide.