Ok...so by "entering" we are talking about a part of a player touching the playing floor in the semi circle...not an arm or rear end crossing the plane of the FT line?
I guess if we use the provision of the marked lane spaces/lines then yes...
it's not a violation for any lane players to put their arms out in front of them into the lane but if they step across and touch, we would have a delayed violation on the D and an immediate violation by the O in that case.
So the ball is in flight and the D player moves to box out position, their butt crosses over the FT line at shooters waist and does not contact, he hasn't "entered" the semi circle...Got it! 😕
Do we dare ask the class to define enter? 😛