Internal implementation package not meant for direct consumption. Please do not reference directly. Provides base classes, including System.Runtime.InteropServices.CriticalHandle and System.Runtime.InteropServices.SafeHandle, for types that represent operating system handles. Commonly Used Types: System.Runtime.InteropServices.SafeHandle Microsoft.Win32.SafeHandles.SafeWaitHandle System.Runtime.InteropServices.CriticalHandle System.Threading.WaitHandleExtensions System.IO.HandleInheritability When using NuGet 3.x this package requires at least version 3.4.