For 25 years I have used this. Unsure rope terms, call it a running hitch and non locking so good to secure limbs for lowering or say pulling over trunks. I hope to share and have peer reviewed as a simple quick easy knot for tree timber handling. I could whip the rope around a limb and tie the knot with one hand so it was high use when I was climbing for a living. Its never failed me and always easy to unlock even after heavy tension. I'll try to explain how its tied but pictures are always better. The only trick hard to show or explain is the turn/twist a loop that the line end passed though.
Why I ask? it was never shown to me, I just muffed it one day and it worked but not seen it else where.