Recently, I encountered a use case of crossover domain that worth blogging about.
The concept of crossover domain is simple. It is a way to trigger something to happen when an attribute is being populated. That something is to copy one or more attributes from a related object to the current object that is involved in the operation at this moment. For example, you want to “crossover” the item’s description when you are putting the item on the purchase order that you are creating.