Translations:A2plus Workbench/43/en

From FreeCAD Documentation

Select either a closed edge or a plane on both parts. The toolbar button adds the constraint centerOfMass. The constraint dialog allows you to specify an offset between the edges or planes. This offset can also be flipped. You can furthermore set the constraint direction and lock the rotation of the parts. If the offset is zero, the constraint will put the edges or planes into the same plane.