Alias IDs enable you to associate a property or class in one object store with an equivalent property or class in another object store.
By assigning alias IDs, you enable support for multi-object store searches.
Only user-defined and built-in properties and classes can be aliased. System classes cannot be aliased.
An object in one object store can be aliased only to one object in another object store. The mapping must be one-to-one between object stores. Aliasing creates an association between objects in different object stores that are functionally identical, and there should be only one of those in each object store.
To perform a cross object store search and retrieve the same value for equivalent properties in each of the object stores, create an alias between the properties.
To assign an alias ID to a property: