I was immediately worried I'd not be let on the site and maybe relegated to scraping bones back at camp. Both me and my boots were assigned to a square. There was a valid reason for the tread thing. Treads can tear up earth floors and other delicate features, as well as leave confusing marks in photographs. I agree with it now, but wish I had known earlier.
Many excavations now warn inexperienced diggers in advance of such things.
Square is one of many terms which were new to me. Each dig has already been divided up into squares. Each square is 6 meters to a side on our excavation. You will not dig 36 square meters at first. This helps insure a lack of contamination between your square and others so that materials do not fall in which do not belong or can confuse the interpretation of the site.