/errors/date_error.proto 

--- v22/errors/date_error.proto 2026-01-23 15:36:22.000000000 +0000
+++ v23/errors/date_error.proto 2026-01-23 15:36:26.000000000 +0000
@@ -66,5 +66,13 @@

     // Both dates in range are null.
     DATE_RANGE_MINIMUM_AND_MAXIMUM_DATES_BOTH_NULL = 10;
+
+    // This campaign type doesn't support a start date time that isn't the start
+    // of the day.
+    DATE_RANGE_ERROR_START_TIME_MUST_BE_THE_START_OF_A_DAY = 13;
+
+    // This campaign type doesn't support an end date time that isn't the end of
+    // the day.
+    DATE_RANGE_ERROR_END_TIME_MUST_BE_THE_END_OF_A_DAY = 14;
   }
 }