diff --git a/reference/strings/functions/htmlentities.xml b/reference/strings/functions/htmlentities.xml
index 57f1c34468..298689a0ac 100644
--- a/reference/strings/functions/htmlentities.xml
+++ b/reference/strings/functions/htmlentities.xml
@@ -78,8 +78,11 @@
           <row>
            <entry><constant>ENT_SUBSTITUTE</constant></entry>
            <entry>
-            Replace invalid code unit sequences with a Unicode Replacement Character
-            U+FFFD (UTF-8) or &amp;#FFFD; (otherwise) instead of returning an empty string.
+            Replace invalid code points for the given document type with a
+												Unicode Replacement Character U+FFFD (UTF-8) or &amp;#FFFD;
+												(otherwise) instead of returning an empty string. This may be
+												useful, for instance,	to ensure the well-formedness of XML documents
+												with embedded external content.
            </entry>
           </row>
           <row>
diff --git a/reference/strings/functions/htmlspecialchars.xml b/reference/strings/functions/htmlspecialchars.xml
index 095c53faeb..3464e8520a 100644
--- a/reference/strings/functions/htmlspecialchars.xml
+++ b/reference/strings/functions/htmlspecialchars.xml
@@ -122,8 +122,10 @@
           <row>
            <entry><constant>ENT_DISALLOWED</constant></entry>
            <entry>
-            Replace code unit sequences, which are invalid in the specified document type,
-            with a Unicode Replacement Character U+FFFD (UTF-8) or &amp;#FFFD; (otherwise).
+            Replace invalid code points for the given document type with a
+            Unicode Replacement Character U+FFFD (UTF-8) or &amp;#FFFD;
+            (otherwise) instead of returning an empty string. This may be
+            useful, for instance, to ensure the well-formedness of XML documents            with embedded external content.
            </entry>
           </row>
           <row>