Discretion Module Tutorial
From ASSS Wiki
This tutorial is divided into a few pieces. If you're completely new to Discretion, you can view them in order, otherwise you can skip to the one you're interested in. It assumes you have no knowledge and nothing installed.
Obtaining the Discretion Source using Subversion
Creating and Testing a Simple Discretion Module
Discretion Commands and Displaying Images (Also covers listening for callbacks and using interfaces)
Listening for Key Presses, Displaying Text, and Per Player Data