Dia is designed to be much like the commercial program 'Visio.' It can
be used to draw many different kinds of diagrams. It has special
objects to help draw entity relationship diagrams, UML diagrams, SADT,
flowcharts, network diagrams, and simple circuits. It is possible to
add support for new shapes by writing simple XML files, and using a
subset of SVG to draw the shape.

Dia can load and save diagrams to a custom XML format (gzipped by
default to save space), can export diagrams to EPS, PNG, CGM, or SVG
formats, and can print diagrams (including ones that span multiple
pages).