The new function were introduced to mimic the behavior of an existing French cartwall software.
ICartwallItem has Select/Unselect.
ICartwallPageControl has SelectItem/UnselectItem (and will respect the new options regarding interlock).
There are new commands "CARTWALL COLUMN " that will do the same thing as the existing "CARTWALL ", but will automatically be applied to the selected item(s) of the specified column.