diff --git a/appendices/migration70/incompatible.xml b/appendices/migration70/incompatible.xml
index f36b484dd0..93a032f427 100644
--- a/appendices/migration70/incompatible.xml
+++ b/appendices/migration70/incompatible.xml
@@ -7,6 +7,7 @@
  &appendices.migration70.incompatible.variable-handling;
  &appendices.migration70.incompatible.foreach;
  &appendices.migration70.incompatible.integers;
+ &appendices.migration70.incompatible.strings;
  &appendices.migration70.incompatible.removed-functions;
  &appendices.migration70.incompatible.removed-ini-directives;
  &appendices.migration70.incompatible.other;
diff --git a/appendices/migration70/incompatible/strings.xml b/appendices/migration70/incompatible/strings.xml
new file mode 100644
index 0000000000..c3505b67ee
--- /dev/null
+++ b/appendices/migration70/incompatible/strings.xml
@@ -0,0 +1,102 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- $Revision$ -->
+
+<sect2 xml:id="migration70.incompatible.strings">
+ <title>Changes to <type>string</type> handling</title>
+
+ <sect3 xml:id="migration70.incompatible.strings.hex">
+  <title>Hexadecimal strings are no longer considered numeric</title>
+
+  <para>
+   Strings containing hexadecimal numbers are no longer considered to be
+   numeric. For example:
+  </para>
+
+  <informalexample>
+   <programlisting role="php">
+<![CDATA[
+<?php
+var_dump("0x123" == "291");
+var_dump(is_numeric("0x123"));
+var_dump("0xe" + "0x1");
+var_dump(substr("foo", "0x1"));
+?>
+]]>
+   </programlisting>
+   &example.outputs.5;
+   <screen>
+<![CDATA[
+bool(true)
+bool(true)
+int(15)
+string(2) "oo"
+]]>
+   </screen>
+   &example.outputs.7;
+   <screen>
+<![CDATA[
+bool(false)
+bool(false)
+int(0)
+
+Notice: A non well formed numeric value encountered in /tmp/test.php on line 5
+string(3) "foo"
+]]>
+   </screen>
+  </informalexample>
+
+  <para>
+   <function>filter_var</function> can be used to check if a
+   <type>string</type> contains a hexadecimal number, and also to convert a
+   string of that type to an <type>integer</type>:
+  </para>
+
+  <informalexample>
+   <programlisting role="php">
+<![CDATA[
+<?php
+$str = "0xffff";
+$int = filter_var($str, FILTER_VALIDATE_INT, FILTER_FLAG_ALLOW_HEX);
+if (false === $int) {
+    throw new Exception("Invalid integer!");
+}
+var_dump($int); // int(65535)
+?>
+]]>
+   </programlisting>
+  </informalexample>
+ </sect3>
+
+ <sect3 xml:id="migration70.incompatible.strings.unicode-escapes">
+  <title><literal>\u{</literal> may cause errors</title>
+
+  <para>
+   Due to the addition of the new
+   <link linkend="migration70.new-features.unicode-codepoint-escape-syntax">Unicode codepoint escape syntax</link>,
+   strings containing a literal <literal>\u{</literal> followed by an invalid
+   sequence will cause a fatal error. To avoid this, the leading backslash
+   should be escaped.
+  </para>
+ </sect3>
+</sect2>
+
+<!-- Keep this comment at the end of the file
+Local variables:
+mode: sgml
+sgml-omittag:t
+sgml-shorttag:t
+sgml-minimize-attributes:nil
+sgml-always-quote-attributes:t
+sgml-indent-step:1
+sgml-indent-data:t
+indent-tabs-mode:nil
+sgml-parent-document:nil
+sgml-default-dtd-file:"~/.phpdoc/manual.ced"
+sgml-exposed-tags:nil
+sgml-local-catalogs:nil
+sgml-local-ecat-files:nil
+End:
+vim600: syn=xml fen fdm=syntax fdl=2 si
+vim: et tw=78 syn=sgml
+vi: ts=1 sw=1
+-->