diff --git a/index.bs b/index.bs
index 499d6a2f..0110d500 100644
--- a/index.bs
+++ b/index.bs
@@ -12751,6 +12751,60 @@ type is used for representing function values that take no arguments and do not
 return any value.
 
 
+<h3 id="TextDirection" enum>TextDirection</h3>
+
+<pre class="idl">
+    enum TextDirection {
+      "auto",
+      "ltr",
+      "rtl"
+    };
+</pre>
+
+The {{TextDirection}} [=enumerable=] is used to represent text directionality as described in [[!BIDI]].
+
+
+<h3 id="localizable" dictionary>Localizable</h3>
+
+A <dfn export>localizable member</dfn> is a dictionary member whose type is {{LocalizableString}}.
+Such members represent one or more bidirectional algorithm paragraphs when displayed,
+as defined by the bidirectional algorithm’s rules P1, P2, and P3,
+including, for instance, supporting the paragraph-breaking behavior
+of <span class="char">U+000A LINE FEED (LF)</span> characters. [[!BIDI]]
+
+A user agent is expected to honor the Unicode semantics of [=localizable members=].
+
+<pre class="idl">
+    dictionary Localizable {
+      DOMString lang = "";
+      DOMString value = "";
+      TextDirection dir = "auto";
+    };
+    typedef (DOMString or LocalizedValue) LocalizableString;
+</pre>
+
+The {{Localizable/lang}} member specifies the primary language for the {{Localizable/value}} member.
+Its value is a {{DOMString}}.
+The empty string indicates that the primary language is unknown.
+Any other string must be interpreted as a language tag.
+Validity or well-formedness are not enforced. [[!BCP47]]
+
+The {{Localizable/value}} is a {{DOMString}} to be localized.
+
+For the {{Localizable/value}}, the {{Localizable/dir}} member provides the higher-level override of rules P2 and P3
+if it has a value other than <a for=TextDirection enum-value>"auto"</a>. [[!BIDI]]
+
+<div class=example>
+   <pre highlight="webidl">
+       dictionary PaymentItem {
+           required LocalizableString label;
+           required PaymentCurrencyAmount amount;
+           boolean pending = false;
+       };
+    </pre>
+</div>
+
+
 <h2 id="extensibility">Extensibility</h2>
 
 <i>This section is informative.</i>