From the software's readme.html:

	mod_dtcl is  a free/open source implementation  of server parsed
	Tcl, under Apache,  distributed under the terms of  the GNU GPL.
	It allows you to tightly integrate  html with Tcl, a widely used
	scripting language  with many  years of development  invested in
	it. This is an ideal combination, allowing you to greatly extend
	what you could do with plain  html. Because Tcl is such a widely
	used language, there is a  large amount of documentation for it,
	both on  the net  and books.  There are  also many  external Tcl
	modules  that you  can  load into  mod_dtcl,  to create  images,
	access databases, etc.