The "XXXXSource" design pattern in .NET

I noticed there are some classes follows a pattern in .NET framework, especially the TPL. For example

• Task and TaskCompletionSource

• CancellationToken and CancellationTokenSource

I believe there are more, but I didn't record them yet. And there is something not in .NET framework but still follows the same pattern

• PauseToken and PauseTokenSource in this article

So is this a documented design pattern? What is its official name and where can I find its description?