True that
all of the cutting is in the 180 degree arc on the leading half of the end mill. but it seems to me that the cutter is conventional milling as the cutting edge enters the arc and climb milling as it exits the arc with a transition in the middle. Maybe that’s why it’s called slotting instead of conventional or climbing? Those terms do apply when the sides of the slot are being cleaned up or the slot is being enlarged with an end mill smaller than slot width.
But, I could be wrong. I was once.
Tom