Cocoa Scripting refers to Apple’s built-in open scripting support for Cocoa-based applications. While the OpenScriptingArchitecture is available to any application that conforms to the AppleEvent based implementation, the CocoaScripting support from Apple makes it much easier to expose the scriptable elements of object oriented applications.

http://developer.apple.com/documentation/Cocoa/Conceptual/Scriptability/Concepts/ScriptingClasses.html