diff --git a/application/Espo/Core/Field/Date.php b/application/Espo/Core/Field/Date.php
index 7ea44cba4a..fd0626f65d 100644
--- a/application/Espo/Core/Field/Date.php
+++ b/application/Espo/Core/Field/Date.php
@@ -167,6 +167,9 @@ class Date implements DateTimeable
         return self::fromDateTime($dateTime);
     }
 
+    /**
+     * A difference between another object (date or date-time) and self.
+     */
     public function diff(DateTimeable $other): DateInterval
     {
         return $this->getDateTime()->diff($other->getDateTime());
diff --git a/application/Espo/Core/Field/DateTime.php b/application/Espo/Core/Field/DateTime.php
index 21939bfc73..5b5d599350 100644
--- a/application/Espo/Core/Field/DateTime.php
+++ b/application/Espo/Core/Field/DateTime.php
@@ -199,6 +199,9 @@ class DateTime implements DateTimeable
         return self::fromDateTime($dateTime);
     }
 
+    /**
+     * A difference between another object (date or date-time) and self.
+     */
     public function diff(DateTimeable $other): DateInterval
     {
         return $this->getDateTime()->diff($other->getDateTime());
diff --git a/application/Espo/Core/Field/DateTimeOptional.php b/application/Espo/Core/Field/DateTimeOptional.php
index 9c8b5d3ac3..d58d3beeb8 100644
--- a/application/Espo/Core/Field/DateTimeOptional.php
+++ b/application/Espo/Core/Field/DateTimeOptional.php
@@ -262,6 +262,9 @@ class DateTimeOptional implements DateTimeable
         );
     }
 
+    /**
+     * A difference between another object (date or date-time) and self.
+     */
     public function diff(DateTimeable $other): DateInterval
     {
         return $this->getDateTime()->diff($other->getDateTime());