An empty slot object can be placed within a free slot in the same
way as a card. Graphically,
IltEmptySlot
objects only differ from free slots by a dark grey label.
Empty slots can represent alarms and states
graphically; however, their base representation cannot be changed.
In other words, a state that would induce a change in the graphic
representation of the object base is ignored.
You should associate an empty slot with a
free slot if you want to manage this free slot in some way. Unlike
an empty slot, a regular free slot is not considered a business
object and cannot represent alarms or states by itself.