Distance arrow reminder

Its been so long since my cave classes. Do distance arrows indicate distance to the entrance or to cave entrances. I mean in Eagle's nest do distance arrows indicate distances to the top of the ballroom (the actual entrance)or the top of the debri cone on the bottom(the centre of that room)? This info changes my planning by a minute or so...

Thanks guys.....

According to my instructor, it's the distance to the point at which you can make a free ascent to the surface.