Certain special dictionaries can be opened directly in Script Debugger.

• To open the dictionary of an installed scripting addition, choose File > Open Dictionary > Scripting Additions. (The keyboard shortcut for this command is likely to become one of your most frequently used shortcuts.)
• To open the AppleScript Studio dictionary, choose File > Open Dictionary > AppleScript Studio.
• To open AppleScript’s internal dictionary, choose File > Open Dictionary > AppleScript.

AppleScript’s internal dictionary is the 'aeut' resource, contained in the AppleScript component file. It can be helpful for explaining certain terminology clashes, as it is the only way to learn what terms are defined by AppleScript. (For example, why can’t you name a global variable “keystroke”? This dictionary tells you.) Within this dictionary, only the AppleScript Suite, the Standard Suite, the Text Suite, and the Type Names Suite are actually enabled. Even though you can see the other suites, they are turned off and do not actively define any terminology (and should be ignored).