This actor object has two properties, “name” and “mbox”. In both cases, and with actor properties in general, the values of these properties are arrays. This facilitates the consolidation of identifiers and descriptive parts of an actor. Sally may have multiple email addresses (in the “mbox” field), and, though less likely, she may go by multiple names, which all comprise a view of Sally the person. At any rate, only “mbox” uniquely describes this Sally. There may be many people out there with the name Sally, but only one of them owns the email address sally@example.com.
sally@example.com.