Objects can be also relatively positioned vertically. This means that the objects can be vertically re-located to a position that is a settable proportional distance down the enclosing frame width. A positioning around 50% would center the object in the enclosing frame.
The origin for the vertical positioning is the top of the frame which would enclose all selected objects.
After clicking the function icon, a dialogue box appears in which you can enter the relative position in percent.