I intend to orphan the dia package.
There seems to be few upstream activity other than translation
updates. I will upload a new version soon and also put
everything in collab-maint git to ease future maintenance.
The package description is:
Dia is an editor for diagrams, graphs, charts etc. There is support for UML
static structure diagrams (class diagrams), Entity-Relationship diagrams,
network diagrams and much more. Diagrams can be exported to postscript and
many other formats.