A cross-object store reference is an object-valued property called Allows Foreign Object that references an object in another object store, referred to as a "foreign" object. The "foreign" object store must be in the same FileNet P8 domain.
The Allows Foreign Object property appears on the property template object, and only when it is created. Subsequently it is read-only. By default it is disabled.
When enabled, an object belonging to any object store that the user has access to can be set as the value for defined property, subject only to the restriction that the class specified for the property must exist in the object store of the target object. Once that requirement is satisfied, the intention is for the behavior and operation of an allows-foreign-object property is identical to that of a local object-valued property, for setting and retrieving and for reflective navigation (if specified).
Enabling the Allows Foreign Object property does not require that a foreign object be set; it only allows it if you do try to set it.
In this graphic, an object-valued property (#1) in object store A has a property Allows foreign object (#2) set to true. This allows its value to retrieve an object in object store B (#3).