See video at 3.52
They indicate the position of the upper block .. (second door). Viewed from inside the small chamber.
Are there any real photographs of these marks??
They were obviously made before the upper block was placed and could not have been used/observed for placing.
Therefore they can only have been used to pre-calculate the position of the upper block face relative to the door.
Obviously this dimension was of great importance.
Post Edited (20-Jun-15 00:35)