diff --git a/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/ContactDiaryElement.kt b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/ContactDiaryElement.kt
new file mode 100644
index 0000000000000000000000000000000000000000..56c42f77dde298813cccc33f6963fd1c7b475c56
--- /dev/null
+++ b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/ContactDiaryElement.kt
@@ -0,0 +1,17 @@
+package de.rki.coronawarnapp.contactdiary.model
+
+import java.time.Instant
+
+interface ContactDiaryElement {
+
+    val createdAt: Instant
+
+    val persons: List<Person>?
+    val locations: List<Location>?
+
+    val numberOfPersons: Int?
+        get() = persons?.size
+
+    val numberOfLocations: Int?
+        get() = locations?.size
+}
diff --git a/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/ContactDiaryEntry.kt b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/ContactDiaryEntry.kt
index f750804714bfef14fde452c5a1fbda10795ca2cd..89c74aa45e98b15030b9c1d290a12c4f9080804d 100644
--- a/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/ContactDiaryEntry.kt
+++ b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/ContactDiaryEntry.kt
@@ -3,7 +3,7 @@ package de.rki.coronawarnapp.contactdiary.model
 import java.time.Instant
 
 data class ContactDiaryEntry(
-    val person: Person,
-    val location: Location,
+    val person: List<Person>?,
+    val location: List<Location>?,
     val dateAddedEntry: Instant?
 )
diff --git a/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Location.kt b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Location.kt
index 7ea04e56f00823183858c5a5849d32af26d260e6..b5d6bca266f192326151a9f086e5a4669c10318f 100644
--- a/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Location.kt
+++ b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Location.kt
@@ -1,5 +1,5 @@
 package de.rki.coronawarnapp.contactdiary.model
 
 data class Location(
-    val locationName:String
+    val locationName: String
 )
diff --git a/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Person.kt b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Person.kt
index 5088f0c6b55f1cfbb03f708ac6c80561691b0900..72963487648a53f13781f59dade102286d2b421a 100644
--- a/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Person.kt
+++ b/Corona-Warn-App/src/main/java/de/rki/coronawarnapp/contactdiary/model/Person.kt
@@ -1,5 +1,5 @@
 package de.rki.coronawarnapp.contactdiary.model
 
 data class Person(
-    val completeName:String
+    val completeName: String
 )