The Generic Diagram Editor
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Diagrams that are made by a diagram editor are a special
kind of graph consisting of nodes and edges and with a certain
representation. In the representation of a graph, nodes and edges are
shown as shapes (boxes, lines, diamonds etc.).
 
Documents should satisfy certain constraints. Most constraints
are specific for the particular diagram technique supported by the
editor. The TGD has almost no constraints. The constraints TGD has
are all built-in constraints which are constraints which can never be
violated because there is no command in the user interface to achieve
that.
 
TGD tool is intended for arbitrary diagrams, not covered by one of 
the other diagram editors. There are almost no immediately
enforced constraints and no soft constraints on these generic
diagrams.

The node and edge tiled buttons each have a little pull-down menu 
with the default node and edge line style (solid, dashed or dotted).
Nodes can have an extra 'index' text label. These are created and
can be edited when the toggle button named 'create/edit indexes' is on.