The IPDRDoc element is the top-level container of a set of IPDRs. The document will also define the entity which recorded these IPDRs via the IPDRRec element. The IPDRDoc.End element optionally marks the end of the IPDR block. It may contain some check information like a count of IPDRs. The IPDRRec element describes the entity that is responsible for creating (recording) the IPDRDoc. The IPDRRecRef element may be used to associate common references to the same IPDRRec element without repeating its other usage attributes. The IPDRRecList identifies contributing IPDR recording entities which were used in the construction of the current IPDR Document. A typical example use would be for an aggregator of IPDR documents to identify the set of initial recorders presenting IPDRs. An IPDR describes an event between a Service Consumer (SC) and a Service Element (SE). The SC and SE elements are contained beneath an entity called the Service Session (SS). Details of the event is contained in the Usage Entry (UE) element. All IPDRs have a time indicating when the event occurred. The Service Session (SS) element groups the Service Consumer and Service Element information. This grouping allows an SC/SE pair to be associated with other IPDRs via a single reference (the SSRef). This is the base type for the Service Consumer element. The service specific schema can extend this by deriving from it. This element describes the Service Consumer. This is the base type for the SE (Service Element)element. The service specific schema can extend this by deriving from it. This element describes the Service Element. This is the base type for the UE (Usage Entry) element. The service specific schema can extend this by deriving from it. This element describes the Usage Entry. The SSRef element may be used to associate common references to the same pairing of a Service Consumer and a Service Element. The SERef element may be used to associate common references to the Service Element. The SCRef element may be used to associate common references to the Service Consumer. The BaseIPDR element allows reference to be made to IPDRs which contributed to the construction of the current IPDR element.