Envelope Snap to horizontal center line

[Phazma]

So there is this horizontal line in the middle envelope lanes. For sure there is a way to make points snap at that line (which would be very handy)? Or does it have some other use which I can't see?

[wolfdogg]

https://www.youtube.com/watch?v=Un719m_7pNc

[Phazma]

Great informative video but it doesn't mention the envelope center line (or generally the horizontal envelope lines for that matter) with any word.