A starting point occurs as dynamically-typed, extensile descriptor format known as an AEDesc, which is good an OSType code specifying the information nature and severity, together by using the prevent of nature and severity-dependent information. For example, a OSType code 'inte' indicated that the information was a quatern-byte sign-language whole number inside big-endian format.

Besides predefined nature and severity codes for various most common elementary types, there are deuce predefined integrated descriptor types: an AERecord, which got information nature and severity 'reco' (record), & AEList sustaining nature and severity 'listing' (listing or even array). the internal structure one contain recursively-nested AEDescs, when a AERecord likewise associated from each one element sustaining a unique record field ID, which is an OSType. A Apple Event Manager provids API calls to construct these structures, when well as extract their contents & query a nature and severity of contents it hang on to.

A Apple Event Manager besides supports coercions, which converts AEDescs from either 1 information nature and severity to a second. Additionally to standard coercions (for example between whole number & really types), applications might set up their have coercion handler callbacks, which could e.g. address conversions to & from either customised information types.

An Apple Event proper is an AERecord using fields that depended on the purpose of the event. Additionally, it has attributes (which are then then distinct from either record fields, which are okay, known as a parameters of the event) from either the placed predefined per Apple Event Manager, specifying such items when a event nature & severity & class codes which indicates what a event is supposed to launder (two OSTypes), the target location to which the event is to become sent (which can be a run on the local or even a remote machine), and various more choices for treating it. Remote machines ab initio got to become attached via AppleTalk, but Mac OS 9 added the guide for modems via TCP/IP.

When sending an AppleEvent to its target run, the sending run can elect to receive a reply. This is likewise an Apple Event, which can contain various bits of data returned from either a target all about a processing of the asking event, including an error even code indicating success/failure, or any more appropriate reference.

Apple Cases come a foundation of the AppleEvent Object Model, which in turn is the foundation of AppleScript.