Linkage is often important to WorldServer because it is used by the system to determine which assets are valid candidates for translation.
Suppose, either manually or automatically (for example, via a Business Rule), twenty different assets are selected for potential translation from English to German. When you create a project, you can specify that WorldServer process only New or Changed assets.
WorldServer determines, via the linkage rules that have been configured, which target asset maps to each source asset and then determines whether each source asset has been updated (that is, has a newer timestamp) than the corresponding target asset.