An “sdef” (pronounced “ess-deaf”, and standing for “scripting definition”) is a new dictionary format, starting in Tiger (Moac OS X 10.4). Script Debugger takes advantage of this new format. Relatively few applications actually use this new format, though, so Script Debugger translates the old format (called an ‘aete’) into the new format before presenting the dictionary to you. As the new format comes into more common use, it will be possible for application authors to provide more accurate, informative dictionaries.

If you use an application with an ‘aete’ dictionary that allows the dictionary to be extended through plug-ins (such as QuarkXPress or InDesign), read the discussion of Script Debugger’s dictionary caching mechanism.