diff --git a/index.html b/index.html
index a5e3fa0d0..779c5addd 100644
--- a/index.html
+++ b/index.html
@@ -1186,6 +1186,14 @@ <h3>Errors</h3>
    could not be satisfied because the window could not be found.
  </tr>
 
+ <tr>
+  <td><dfn>no such script</dfn>
+  <td>404
+  <td><code>script timeout</code>
+  <td>No script matching the given script name was found amongst the
+  <a>list of known scripts</a> of the current session.
+ </tr>
+
  <tr>
   <td><dfn>script timeout error</dfn>
   <td>500
@@ -2111,6 +2119,8 @@ <h2>Sessions</h2>
 A <a>session</a> has an associated <a>user prompt handler</a>.
 Unless stated otherwise it is in the <a>dismiss and notify state</a>.
 
+<p>A <a>session</a> has an associated <a>executable script map</a>.
+
 <p>A <a>session</a> has an associated list of <a>active input sources</a>.
 
 <p>A <a>session</a> has an associated <a>input state table</a>.
@@ -5871,7 +5881,38 @@ <h3><dfn>Get Page Source</dfn></h3>
 </section> <!-- /Get Page Source -->
 
 <section>
-<h3>Executing Script</h3>
+ <h3>Scripts</h3>
+
+ <p>
+  An <dfn>executable script</dfn> is an abstraction used to
+  identify a script when it is transported via the
+  <a href="#protocol">protocol</a>, between <a>remote</a> and
+  <a>local</a> ends.
+
+  Each script may include an optional associated <dfn>executable script name</dfn>
+  that uniquely identifies the script within the <a>current session</a>.
+
+  Each <a>session</a> maintains an <a>ordered map</a> <dfn>executable script map</dfn>,
+  with each entry having a key of an <a>executable script name</a>
+  and a value of an <a>exeuctable script</a>.
+  This map is initially empty.
+
+  To add an <a>executable script</a> to the session,
+  for <a>executable script map</a>, key <a>executable script name</a>, and value <var>script</var>,
+  set map[key] to value.
+
+  To remove an <a>executable script</a> from the session,
+  for <a>executable script map</a>, key <a>executable script name</a>, and value <var>script</var>,
+  remove map[key].
+
+  To <dfn>get a script</dfn> with argument <var>name</var>, run the following steps:
+ <ol>
+  <li>If <var>name</var> is not equal to a key in the <a>executable script map</a>
+   for the <a>current session</a>, return <a>error</a> with <a>error code</a>
+   <a>no such script</a>.
+  <li>Let <var>script</var> be the value in the <a>executable script map</a>
+   associated with the key <var>name</var>.
+ </ol>
 
 <p>
 A <dfn>collection</dfn> is an <a>Object</a>
@@ -6049,9 +6090,15 @@ <h3>Executing Script</h3>
   <a>getting a property</a> named <code>script</code>
   from the <var>parameters</var>.
 
+ <li><p>If <var>script</var> is set and <var>name</var> is set,
+ return <a>error</a> with <a>error code</a> <a>invalid argument</a>.
+
  <li><p>If <var>script</var> is not a <a>String</a>,
   return <a>error</a> with <a>error code</a> <a>invalid argument</a>.
 
+ <li><p>If <var>name</var> is set let <var>script</var> be the result
+ of <a>trying</a> to <a>get a script</a> with argument <var>name</var>
+
  <li><p>Let <var>args</var> be the result of
   <a>getting a property</a> named <code>args</code>
   from the <var>parameters</var>.
@@ -6153,6 +6200,10 @@ <h3><dfn>Execute Script</dfn></h3>
 <p>The <a>remote end steps</a> are:
 
 <ol>
+ <li><p>Let <var>name</var> be the result of
+  <a>getting a property</a> named <var>name</var>
+  from the <var>parameters</var>.
+
  <li><p>Let <var>body</var> and <var>arguments</var> be the result of
   <a>trying</a> to <a>extract the script arguments from a request</a>
   with argument <var>parameters</var>.
@@ -6216,6 +6267,10 @@ <h3><dfn>Execute Async Script</dfn></h3>
 <p>The <a>remote end steps</a> are:
 
 <ol>
+  <li><p>Let <var>name</var> be the result of
+     <a>getting a property</a> named <var>name</var>
+     from the <var>parameters</var>.
+
   <li><p>Let <var>body</var> and <var>arguments</var> by the result of <a>trying</a> to
      <a>extract the script arguments from a request</a> with
      argument <var>parameters</var>.
@@ -6281,7 +6336,45 @@ <h3><dfn>Execute Async Script</dfn></h3>
       and data <var>result</var>.
 </ol>
 </section> <!-- /Execute Async Script -->
-</section> <!-- /Executing Script -->
+<section>
+ <h3><dfn>Pin Script</dfn></h3>
+
+ <table class="simple jsoncommand">
+  <tr>
+   <th>HTTP Method</th>
+   <th>URI Template</th>
+  </tr>
+  <tr>
+   <td>POST</td>
+   <td>/session/{<var>session id</var>}/execute/pin</td>
+  </tr>
+ </table>
+
+ <p>The <a>remote end steps</a> are:
+
+  <ol>
+   <li><p>Let <var>name</var> be the result of
+ <a>getting a property</a> named <var>name</var>
+ from the <var>parameters</var>.
+
+ <li><p>Let <var>script</var> be the result of
+ <a>getting a property</a> named <var>script</var>
+ from the <var>parameters</var>.
+
+ <li><p>If <var>script</var> is <a>undefined</a> or is not a <a>String</a>,
+ return <a>error</a> with <a>error code</a> <a>invalid argument</a>.
+
+ <li><p>If <var>name</var> is <a>undefined</a> or is not a <a>String</a>,
+ return <a>error</a> with <a>error code</a> <a>invalid argument</a>.
+
+ <li><p>If <var>name</var> is equal to a key in the <a>executable script map</a>
+ remove the <a>executable script</a> from the session
+
+ <li><p>add the <a>executable script</a> to the session.
+
+ </ol>
+</section> <!-- /Pin Script -->
+</section> <!-- /Scripts -->
 </section> <!-- /Document -->