Ada Programming/Libraries/Ada.Asynchronous Task Control

is a unit of the Predefined Language Environment since Ada 95.

Specification
Preelaborate Asynchronous_Task_Control Hold T  AdaTask_IdentificationTask_Id Continue T  AdaTask_IdentificationTask_Id Is_Held T  AdaTask_IdentificationTask_Id  Boolean AdaAsynchronous_Task_Control

Wikibook

 * Ada Programming/Libraries/Ada