You could have downloaded PNEditor 0.51 for Mac from our software library for free. This free software for Mac OS X is a product of Martin Riesz. The application lies within Internet & Network Tools, more precisely Network tools.
From the developer:
PNEditor is a neat, easy-to-use Petri Net editor.
Main features:
- Petri net editor
- Subnets
- Role definitions
- Static places (shared resources)
- PNML import and export (Viptool non-standard dialect)
- EPS and PNG export
Requirements: Java SE 6+.
You may want to check out more software for Mac, such as IPNetShareX, tn3270 or Remote Connections Manager, which might be related to PNEditor.