What are references?

References are relationships of dependency between items within configuration, for example, where a particular district references its immediate neighbours. There can be many thousands of references in configuration.

We use the following terminology:

• An item's dependencies are the items it references.
• An item's dependents are the other items that reference it.
• Direct dependency is where one item depends directly on another. For example, A references B.
• Indirect dependency is where you have a chain of dependency, for example, A references B, which references C. In this case, C is an indirect dependency of A.
• Circular dependency is where you have items that reference each other, directly or indirectly, for example where A references B, and B references A. This can occur with adjacent districts that reference each other.
• A bad reference is where the reference cannot be resolved.

Xoom resolves direct, indirect and circular dependencies. References are indicated in XoomXML by the xoom:ref attribute, which takes the value of the Xoom identity to which it points.