JEITA  CP-3451 - 65 - 4.7.3   Interoperability Structure of APP2 in Compressed Data APP2 consists of an APP2 marker indicating that it is an  application area, a  length code indicating its size, and Flashpix (see Annex F) extensions. If there is no need to record extensions, this marker segment may be omitted.   There are two kinds of APP2 marker segments for recording Flashpix extensions. One is a Contents List Segment recording a storage and stream list making up the extended data. One file contains only one contents list segment.   The second is a Stream Data Segment storing the data for each of the streams listed in the Contents List Segment. If necessary, there may be two or more APP2 marker segments for storing stream data.   In addition there is an APP2 segment reserved for Flashpix use, which is specified in the Flashpix standard. The contents of data that can be recorded as stream data is left for future specification. It may include one or more Audio data. A.    Order of APP2 recording. APP2 segments follow after the APP1 segment, in the order of Contents List Segment and Stream Data Segments. If there are two or more stream data segments, their order is as given in the contents list (see Figure 6). B.    APP2 Interoperability structure APP2 consists of an APP2 marker, ID code (FPXR), and Contents List or Stream Data (see Figure 26). Address Offset Code Meaning (Hex) (Hex) +00 FF Marker Prefix +01 E2 APP2 +02 Length of field +04 46 'F' +05 50 'P' +06 58 'X' +07 52 'R' +08 00 NULL +09 00 Version +0A Contents List or Stream Data Figure 26 Basic Structure of APP2 Marker Segment C.    FPXR ID code The FPXR ID code indicates that the APP2 segment contains FPXR data. It is a 4-byte  code followed by 00.H recorded in 1 byte. The reason for recording this code is to avoid duplication with other applications making use of JPEG application marker segments (APPn). The subsequent byte gives the version number (00.H). D.    Contents list structure The contents list segment lists the storages and streams to be created when the file is converted to a Flashpix image file. The first two bytes give the number of Interoperability. The Interoperability fields on the contents list are as follows.