Abstract: An apparatus for continuously and adjustably subdividing a space. The apparatus contains front and rear rails, each having a rail aperture and a rail channel, a divider panel, and a first fastener and a second fastener that can be inserted into the rail aperture of the front and rear rails, respectively, and can be retained within the rail channel of the front and rear rails, respectively. Widened notches are formed in the rails more than a minimum subspace distance from surface intersections, so that fasteners for subspace-defining structures or subspace-functional elements can be inserted and removed. Preferably, the rails are inset flush with the interior surfaces of the interior space.