Timeliner has been developed as a tool to automate procedural tasks. These tasks may be sequential tasks that would typically be performed by a human operator, or precisely ordered sequencing tasks that allow autonomous execution of a control process. The Timeliner system includes elements for compiling and executing sequences that are defined in the Timeliner language. The Timeliner language was specifically designed to allow easy definition of scripts that provide sequencing and control of complex systems. The execution environment provides real-time monitoring and control based on the commands and conditions defined in the Timeliner language. The Timeliner sequence control may be preprogrammed, compiled from Timeliner "scripts," or it may consist of real-time, interactive inputs from system operators.Historically, Timeliner was created to emulate the timelines for onboard crew procedures followed by the crew of the Space Shuttle. It was used as a simulation driver in tests of the Space Shuttle system, mimicking crew actions in monitoring and controlling the spacecraft systems. This version of Timeliner has been in use since 1982. The Timeliner simulation system was extended for use in other applications, and was tailored to provide real-time sequence execution and support interactive control commands that mi ' o ht be entered by the systems engineer: for example, sequence start and stop.In 1992, NASA selected Timeliner as the User interface Language (UIL) for Space Station Freedom, and later for International Space Station (iSS) to be executed on the Space Station's real-time core command and control and payload control computers. Since that time, Timeliner has evolved as a modular, extensible system that allows scripts to be developed and executed in virtually any systems environment; Timeliner can be applied to control a variety of target systems and meet a wide range of mission objectives. It is currently in use on the Space Station for U.S and Japanese core and payload operations. In addition, an extended version of the real-time ISS Timeliner system is to be used throughout the U.S. by several academic institutions and NASA centers as a UNIX-based, general-purpose, procedure executor for ISS payload development, simulation and test environments In general, the Timeliner system lowers the workload for mission or process control operations. In a mission environment, scripts can be used to automate spacecraft operations including autonomous or interactive vehicle control, performance of preflight and post-flight subsystem checkouts, or handlingof failure detection and recovery. Timeliner may also be used for mission payload operations, such as stepping through pre-defined procedures of a scientific experiment.For the International Space Station, Timeliner provides significant mission cost savings and productivity gains. Since Timeliner executes multiple automated sequences in parallel, multiple operations and experiments can occur simultaneously, utilizing the Space Station crew members for only the `human ...