windows - What is [not] an audio endpoint? -

Excerpt from choosing a blog piece entitled to one of the main architects of the post-XP Windows Audio System:

• An endpoint is a "piece of plastic" (hopefully some stars are expected in it) "Users who are related" such as "microphone or headset connected to your laptop".

That looks great except that I have ever used on every desktop machine in the last 15 years, a microphone and a line-in input jack, and they have the same status Together (at least in my mind) are present as a user, I strongly relate to "pieces of plastic", I'm connected to a line-in jack. They definitely have trouble finding me too much like an audio endpoint:

• When I find IMMDeviceEnumerator and < Code> IMMDeviceColltion , and use Microsoft's own example code (like "CaptureShared Timer Drain" audio sample in Microsoft's SDK) they only list microphones as a closing point

So if my line-in jack is not an audio endpoint, then what is this, how I can get it, I'm setting the volume on it, and so on How can I use an app (exclusively) even when the user has chosen the microphone as the default endpoint?

Partial (and Confused) Answer: Listed as an audio endpoint for a microphone It is possible, even if there is no connection to the microphone jack, but a line-in input can only be listed and can validate itself as the audio endpoint when a device is physically attached to the line-in jack It does not have any obvious meaning, but still the way things are ... at least on my machine.