Updated Photos version 5 database (markdown)

Photos-version-5-database.md

@@ -118,7 +118,7 @@ Photos modifies `ZMODIFICATIONDATE` even for photos that have not been edited.
 
 On export, Photos does not set the EXIF modify date.
 
-### import method
+### Import method
 In Photos 5, referenced photos appear to be identified by `ZGENERICASSET.ZSAVEDASSETTYPE`:
 
 - 3: imported by copying to Photos library
@@ -127,6 +127,34 @@ In Photos 5, referenced photos appear to be identified by `ZGENERICASSET.ZSAVEDA
 - 10: referenced file (not copied to Photos library)
 
 
+### Burst Photos
+Burst photos are identified by a burstUUID and a burstPickType.  (In Photos 5+ these are called "avalanche" instead of burst.
+The "pick type" seems to be a bit flag indicating status of images in the burst set:
+
+    In Photos <=4, these values are in `RKVersion.burstUuid` and `RKVersion.burstPickType`
+    In Photos >= 5, these values are in `ZGENERICASSET.ZAVALANCHEUUID` and `ZGENERICASSET.ZAVALANCHEPICKTYPE` (ZASSET table in Photos 6)
+
+The values appear to be:
+
+BURST_NOT_SELECTED = 0b10 # 2: burst image is not selected
+BURST_SELECTED = 0b1000 # 8: burst image is selected
+BURST_KEY = 0b10000 # 16: burst image is the key photo (top of burst stack)
+BURST_DEFAULT_PICK = 0b100 # 4: burst image is the one Photos picked to be key image before any selections made
+BURST_UNKNOWN = 0b100000 # 32: this is almost always set with BURST_DEFAULT_PICK and never if BURST_DEFAULT_PICK is not set.  I think this has something to do with what algorithm Photos used to pick the default image
+
+Thus, an unselected burst image has a value of 2.
+A selected image could be
+
+    8: BURST_SELECTED
+    12: BURST_SELECTED & BURST_DEFAULT_PICK
+    44: BURST_SELECTED & BURST_DEFAULT_PICK & BURST_UNKNOWN
+
+A key image could be:
+
+    16: BURST_KEY
+    20: BURST_KEY & BURST_DEFAULT_PICK
+    52: BURST_KEY & BURST_DEFAULT_PICK & BURST_UNKNOWN
+
 **TODO** Document the following
 
 * [ ] Joining assets