Introduced with the December 2001 developer tools and/or OS X 10.1.2, AppleScriptStudio (or - short and naughty - ASS) refers to the combination of tools (ProjectBuilder and InterfaceBuilder) and frameworks that allow an AppleScript application to access Cocoa objects. You can even mix AppleScript and Cocoa code within the same application.

More info here: http://developer.apple.com/techpubs/macosx/CoreTechnologies/AppleScriptStudio/index.html

Also, if you’ve got ASS already installed with the Dec 2001 dev tools, check your hard drive here:

file:///Developer/Documentation/CoreTechnologies/AppleScriptStudio/

More currently if you have 10.4.x an ASS tutorial can be found at:

file:///Developer/ADC%20Reference%20Library/documentation/AppleScript/Conceptual/StudioBuildingApps/index.html

and reference at:

file:///Developer/ADC%20Reference%20Library/documentation/AppleScript/Reference/StudioReference/index.html