The Notification Manager provides routines that allow software running in the background (or otherwise unseen by the user) to communicate information to the user.
Inside Macintosh: Processes (Chapter 5 - Notification Manager) This document describes the parts of the Macintosh system software that allow you to manage processes and tasks. Chapter 5 describes how to use the Notification Manager and includes an overview, a tutorial, and a complete API reference.
[