The default file format for any file created with Dia is. You can create UML diagrams, flowcharts, network processes and architectures, entity relationship diagrams, etc. Dia is an open-source program very similar to Microsoft Visio, with largely the same feature set. You can easily group different objects together and then do different actions on the group like moving the group, connecting with other groups, etc. The feature that I love in Draw is the grouping feature.
