Functions in the os (Operating System) API:
os.version()
os.getComputerID()
os.getComputerLabel()
os.setComputerLabel()
os.run( environment, programpath, arguments )
os.loadAPI( path )
os.unloadAPI( name )
os.pullEvent( [filter] )
os.queueEvent( event, arguments )
os.clock()
os.startTimer( timeout )
os.cancelTimer( token )
os.sleep( timeout )
os.time()
os.day()
os.setAlarm( time )
os.cancelAlarm( token )
os.shutdown()
os.reboot()

Events emitted by the os API:
"timer" when a timeout started by os.startTimer() completes. Argument is the token returned by os.startTimer().
"alarm" when a time passed to os.setAlarm() is reached. Argument is the token returned by os.setAlarm().
Type "help events" to learn about the event system.