To view an application’s AppleScript dictionary:

In Script Editor, choose Window > Library.

Double-click the name of the application in the Library window.

Select a suite.
The terms belonging to the suite and their descriptions are displayed.
A dictionary contains a set of terms that are understood by an application or a scripting addition.
To find out which commands and objects you can use to control an application, you can use Script Editor to look at that application’s dictionary.
Terms in a dictionary are organized into groups of related terms called “suites.” Commands and objects are in bold text and comments are in italics.
In Script Editor, choose Window > Library.
Double-click the name of the application in the Library window.
Select a suite.
The terms belonging to the suite and their descriptions are displayed.
If a scriptable application doesn’t appear in the Library, see: