A more recent example is found in the Masons loft of York minster. Masons used the floor to draw patterns for the framework of the church stonework. The plaster could be scratched to form clean white lines, and then brushed off and reused to create different design. Drawings are dated between 1350-1539. see http://www-users.york.ac.uk/~arch40/plasterfloor.htm
"... the surface of the floor in the course of time came to be covered with patterns of straight and curving lines which had no connection with one another. To make sense of any part of the conflicting patterns one must trace all surviving lines and follow out those groups of lines which appear to be related." Vicky Sypsa
Image: Drawing of the tracing floor lines.
The plaster tracing floor makes the invisible translation from horizontal to vertical, from the floor to the wall. The floor forms the base for the creation of the windows and carries a memory.