diff --git a/reference/datetime/book.xml b/reference/datetime/book.xml
index 9a193c1824..f5257f7f6b 100644
--- a/reference/datetime/book.xml
+++ b/reference/datetime/book.xml
@@ -16,8 +16,9 @@
    date and time in many different ways.
   </para>
   <para>
-   Each component of date (e.g. year) is internally stored as 64-bit number so
-   all imaginable dates (including negative years) are supported.
+   The date and time information is internally stored as an 64-bit number so
+   all imaginable dates (including negative years) are supported. The range is from about 292
+   billion years in the past to the same in the future.
   </para>
   <note>
    <simpara>
diff --git a/reference/datetime/dateinterval.xml b/reference/datetime/dateinterval.xml
index 542467762e..b57f127de9 100644
--- a/reference/datetime/dateinterval.xml
+++ b/reference/datetime/dateinterval.xml
@@ -12,7 +12,9 @@
   <section xml:id="dateinterval.intro">
    &reftitle.intro;
    <para>
-    Representation of date interval.
+    Representation of date interval. A date interval stores either a fixed amount of time
+    (in years, months, days, hours etc) or a relative time string in the format that
+    DateTime's constructor supports.
    </para>
   </section>
 <!-- }}} -->