Building coordinates

A new university hall of residence is being assembled close to my house (hopefully it will look better than this when finished):


Walking past, I've notice small yellow tickets attached to each pre-fabricated unit of the building:


I wondered whether they were job numbers, delivery addresses for the unit, return to sender labels or, as it turns out, coordinates to assist in the assembly of the building:

Some years ago, when I moved house, I used the same technique (Post-its) to label the elements of a storage unit that I had to disassemble then reassemble after the move. Somehow I'd expect something more sophisticated in the world of construction.