Procedural objects are useful to place objects based on a rule. There are 2 different rule types you can choose from. - Random or Pattern.
inset only on pattern type:
Random places the object randomly on the selected layer and tile type. The weight defines the probability of being spawned.
The pattern rule can be used to define simple spawn rules.
Some examples below:
Spawn this column on every inverted corner tile with an inset of 1
Spawn this torch light on every second edge tile.