ivtools is a layered collection of application frameworks for building
custom drawing editors and spatial data servers.  It incorporates a
backward compatible copy of the original InterViews and Unidraw class
libraries and sample programs (from 3.2a.tar.Z), augmented with new
class libraries and sample programs for a wide variety of generic
spatial data applications.

ivtools comprises four sets of interrelated capabilities useful to
application programmers.  The first set is the libraries and example
programs borrowed whole from InterViews 3.1.  The second set is for
reusing and extending the light-weight glyph objects of InterViews 3.1
which embody a lot of the capability of TeX.  The third set reuses and
extends the Unidraw library (Unidraw is a major portion of the overall
InterViews 3.1 release that provides an application framework for
custom drawing editors).  The fourth set adds a command interpreter
and server mechanism to ivtools, and demonstrates these capabilities
with text, glyph, and graphic front-ends.  To get more of an overview
of these layers you can read:

    http://www.ivtools.org/ivtools/ivtools-layers.html.