Although an EOAssociation has only one display object it may have any number of aspects. Aspects define the EODisplayGroup characteristics that the association observes. Aspects are bound to a display group by a key of the enterprise objects contained by the association. Depending upon a given EOAssociation subclass, aspects may be optional or mandatory. They might all have to be bound to a single EODisplayGroup or they may span several.
Some aspects can be mutually exclusive.
On the display side, aspects are typically bound to visible facets of the EOAssociation's display object, such as the value or values it displays and any interactive state. Each aspect's value is determined by the contents of the enterprise-object property in the EODisplayGroup that the aspect is bound to. This value may be taken from all enterprise objects in the EODisplayGroup or only those in the current selection. When focus leaves the text field, the newly entered value is sent to the EODisplayGroup. As EODelayedObservers, EOAssociations add themselves to the list of objects observing the display groups they are bound to.