For client packages which utilize ViewerAbort, the user who has started some action in a viewer and then wishes to abort it, holds down the left shift key and the swat key (on a Dorado), or the STOP key (on a DLion) in the viewer associated with the action, to cause the action to stop. Note that it may take up to a half second for ViewerAbort to see this key combination, and even then, there is no guarantee how long it will be until the client package decides to check for an abort.

For client packages which perform computation-intensive actions which are associated with a viewer, and which would like to permit a user to abort, ViewerAbort may be the answer. The interface consists of a simple procedure to which the client supplies a viewer and a callback procedure. If the user holds down the left shift key and the SWAT key (or just the STOP key on a DLion) in the associated viewer while in the associated viewer the process is executing the call-back procedure, that process will be aborted, which is to say, that if the client chooses to call Process.CheckForAbort, ABORTED will be raised.