AppleScript is a system language that you can use make OSCulator interact with other Mac applications. It is a fun to use language that can easily yield complex actions.
You can trigger an AppleScript with an OSC message, by writing the little piece of code in the Parameters Window.
It is recommended to use the application “Script Editor” (found in the Applications folder of Mac OS X) to write complex scripts: the results window gives informations about the running script that are not displayed in OSCulator.
Also, you have to bear in mind that AppleScript is not a language designed to be efficient in its speed of execution, but rather powerful in its expression. For that reason, you may not want to trigger AppleScripts too rapidly, or at least give it the time to execute until it is done, or you could experience weird behaviors.