If the transaction is self-contained and also includes media objects to be transcoded, then media objects and the SOAP envelope are included as body parts of a MIME multipart structure as shown in Figure 6.58. The transcoding job part of the transaction request is composed of two sections: a section describing the source (i.e., the media object to be transcoded, e.g., format type, etc.) and another section describing the target (i.e., what result is expected, e.g., user agent profile of the receiving device, etc.). As part of the transaction request, the MMS center may refer to a specific transcoding policy defining the rules to be followed by the transcoder.