Distance on the machine base without aggregates, which can be useful for later a installation of an additional unit. Holes or aggregates stands point to such a free place.

Product variety and desired product quality determine the Aggregate configuration of woodworking machines composed in a modular system. If the requirements for the product are changing, additional units are required. To keep flexible for such changes, some woodworkers choose a longer machinery base than for the current used aggregates necessary.

Some manufacturers offer their machines for reasons of cost with fixed aggregate configurations. In order to adapt their new machine later with additional units, these machines often have free spaces.