Parent-Child reference type

The default reference type is parent-child. The reference type is strong since it allows the child element to have many parents and exist as long as it has one or more strongly related parents. When the last parent element of the child is deleted, the child itself is deleted. Use the parent-child reference type when you want the child element to exist as long as it has a strong reference to at least one parent, but you do not want the child element to be treated as a single unit with the parent element.

Effect of a deleted parent-child reference when that parent-child reference type exists elsewhere

Example

A meter belongs to a company and is attached to a building. You would use a parent-child reference between the Company element and the child Meter element, and another parent-child reference between the Building element and the child Meter element. If the reference between the Meter and the Building element is deleted, the Meter element continues to exist because it has a parent-child reference to the Company element. However, if the child Meter element is also deleted from the Company element, it no longer exists because all parent-child references have been removed.