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About Apple Event Data Structures

Understanding a few key concepts can help things go smoothly in creating an Apple event or working with its data:

• Each piece of information in an Apple event is associated with a four-character code (or in some cases, two such codes).

• A descriptor is a data structure that stores data and an accompanying four-character code. All the information you work with in an Apple event is stored in descriptors and lists of descriptors.

• The content of an Apple event is conceptually divided into two kinds of items, both constructed from descriptors:

  • Attributes identify characteristics of the task to be performed by the Apple event.

  • Parameters provide additional data to be used in performing the task.

• To create an Apple event, extract data from an event, or add data to an event, an application calls Apple Event Manager functions and passes the appropriate four-character codes and other information.

• To operate effectively with Apple events, you just need to find the right function for the task at hand.

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