diff --git a/Photos-version-5-database.md b/Photos-version-5-database.md
index 794f364..cfd53e1 100644
--- a/Photos-version-5-database.md
+++ b/Photos-version-5-database.md
@@ -118,6 +118,13 @@ Photos modifies `ZMODIFICATIONDATE` even for photos that have not been edited.
 
 On export, Photos does not set the EXIF modify date.
 
+### import method
+In Photos 5, referenced photos appear to be identified by `ZGENERICASSET.ZSAVEDASSETTYPE`:
+
+- 3: imported by copying to Photos library
+- 4: shared iCloud photo
+- 6: imported by iCloud (e.g. from iPhone)
+- 10: referenced file (not copied to Photos library)
 
 
 **TODO** Document the following