AppleEvent
An AppleEvent structure is basically a descriptor record (of descriptor type typeAppleEvent) with a handle to a list of keyword-specified descriptor records. As with other Apple Event data structures based on data type AEDesc, purpose for which each is used. The data handles in an Apple event record's
keyword-specified descriptor records of the AppleEvent structure can refer either to attributes or to parameters, whereas the data handles in the
keyword-specified descriptor records of an AERecord can refer only to parameters. Similarly, an AERecord can use only the keywords that identify Apple event parameters, whereas an Apple event record can use keywords that
identify either attributes or parameters.