A ProductOrder represents a request used to procure, update or remove one or many Products in the context of a ProductOffering through all its ProductOrderItems.<br/><i>Note that ProductSpecifications / Products cover 2 cases: 1) ProductSpecifications / Products bought by a Customer to the Service Provider, 2) ProductSpecifications / Products bought by the Service Provider to Business Partners.</i><br/>ProductOrder is a sub-class of RootEntity and therefore inherits from all its attributes and relationships.<br/>At least one CommunicationInteraction is the source of a ProductOrder. Then, additional interactions might happen such as the Customer asking why his order isn’t yet delivered or the Service Provider informing the Customer his order is completed.<br/>A ProductOrder might refer to an Agreement specifying all what has been approved by the PartyRoles involved in the ProductOrder.<br/>A ProductOrder and ProductOrderItems might be further described by Attachments.<br/>A ProductOrderItem may need other ProductOrderItems to be completed; this dependency is represented through the ProductOrderItemRelationship.<br/><br/>ProductOrder / ProductOrderItem are sub-classed as<br/>        • BusinessPartnerProductOrder used to procure, update or remove Products for the Service Provider<br/>        • CustomerProductOrder used to procure, update or remove Products for Customers<br/>