System.Threading (mscorlib.dll)delegate

This delegate is passed to a ThreadPool. If the wasSignaled parameter is true, then the delegate is invoked in response to a signal; otherwise, it is invoked because the handle timed out.

public delegate void WaitOrTimerCallback(object state, bool timedOut);

Passed To

ThreadPool.{RegisterWaitForSingleObject( ), UnsafeRegisterWaitForSingleObject( )}

    Part II: Programming with the .NET Framework
    Part IV: API Quick Reference
    Chapter 26. System