ABL supports events with several different constructs. Classes support widget and built-in object events using the ON statement, and they support ProDataSet, query, buffer, socket object and server socket object callbacks using the SET-CALLBACK() method. Classes also allow you to publish named events associated with external procedures using the PUBLISH statement’s FROM publisher-handle option and they allow you to manage subscriptions of internal procedures as event handlers for named events using the SUBSCRIBE and UNSUBSCRIBE statements’ PROCEDURE subscriber-handle option. However, you cannot subscribe class methods to named events as event handlers or otherwise provide behavior to a class using named events. Classes support class events as members that provide a similar form of event behavior for a class. For more information, see Define events within a class.