JEITA  CP-3451 - 61 - D.    Restart Interoperability definition (DRI: Define Restart Interoperability) DRI is a marker defining the Interoperability at which restart markers are inserted (see Figure 21). The recording of DRI  and  insertion  of  restart  markers  are  optional.  If  restart  markers  are  inserted,  DRI  shall  be  recorded  and  its values shall be 4 MCU (Minimum Coding Unit), i.e., 64 pixel units, regardless of whether 4:2:2 or 4:2:0 is used for color sampling (see Annex F). Only one DRI shall be recorded. DQT, DHT, DRI and SOF may line up in any order, but shall be recorded after APP1 (or APP2 if any) and before SOS. Address Offset Code Meaning (Hex) (Hex) +00 FF Marker Prefix +00 DD DRI +02 00 Length of field 2+2 = 4 (Bytes) +04 XX 00 YY 04 Figure 21 DRI Structure