What was the rationale for choosing exactly 4cm as grid interval?
I am interested in using some open hardware interface in my home furniture project and I'm guessing which grid to chose. There is, for example, american "Grid beam" project which uses 1.5 inch hole spacing. It's obvious that 60 cm is dividable by 4, but there are also tolerances and stacking gaps. So two adjacent structures of exact 60cm side length wont make 120cm but rather 120.5 or 121cm. Which are tolerances and stacking gaps for OS grid?