(Optional) The name by which the entity manager is to be accessed in the environment referencing context; not needed when dependency injection is used.

(Optional) Properties for the container or persistence provider. Vendor specific properties may be included in this set of properties. Properties that are not recognized by a vendor are ignored.

(Optional) Specifies whether a transaction-scoped persistence context or an extended persistence context is to be used.

(Optional) The name of the persistence unit as defined in the persistence.xml file. If the unitName element is specified, the persistence unit for the entity manager that is accessible in JNDI must have the same name.