<col> creates a column structure by arranging all the children objects into a "column" along the y axis.

The first child remains at the same position. The rest of the children are re-positioned in such a way that each child is next to the previous child along the y axis.

In terms of alignment, all objects are aligned to the middle along the x axis and aligned to the min along the z axis. A spacing attribute can be optionally provided to specify how much space to add between every two objects.

In the example below, three cubes of varying sizes are grouped into a column along the y axis, automatically aligned along the other two axes, and have a spacing of 20 between every two cubes.