--- a/encrypted-media/encrypted-media.html	Mon Mar 24 15:15:39 2014 -0700
+++ b/encrypted-media/encrypted-media.html	Mon Mar 24 17:45:28 2014 -0700
@@ -348,7 +348,7 @@
     <p>The <dfn id="dom-mediakeys-constructor"><code>MediaKeys(<var title="true">keySystem</var>)</code></dfn> constructor must run the following steps:</p>
 
     <ol>
-      <li><p>If <var title="true">keySystem</var> is null or an empty string, throw an <code><a href="http://www.w3.org/TR/dom/#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and abort these steps.</p></li>
+      <li><p>If <var title="true">keySystem</var> is an empty string, throw an <code><a href="http://www.w3.org/TR/dom/#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and abort these steps.</p></li>
       <li><p>If <var title="true">keySystem</var> is not one of the user agent's supported <a href="#key-system">Key Systems</a>, throw a <code><a href="http://www.w3.org/TR/dom/#dom-domexception-not_supported_err">NOT_SUPPORTED_ERR</a></code> and abort these steps. Key system string comparison is case-sensitive.</p></li>
       <li>Create a new <code><a href="#dom-mediakeys">MediaKeys</a></code> object.
         <ol>
@@ -383,7 +383,7 @@
     </p>
 
     <ol>
-      <li><p>If <var title="true">contentType</var> is null or an empty string, throw an <code><a href="http://www.w3.org/TR/dom/#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and abort these steps.</p></li>
+      <li><p>If <var title="true">contentType</var> is an empty string, throw an <code><a href="http://www.w3.org/TR/dom/#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and abort these steps.</p></li>
       <li><p>If <var title="true">initData</var> is null or an empty array, throw an <code><a href="http://www.w3.org/TR/dom/#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and abort these steps.</p></li>
       <li><p>If <var title="true">contentType</var> contains an invalid or unrecognized MIME type, throw a <code><a href="http://www.w3.org/TR/dom/#dom-domexception-not_supported_err">NOT_SUPPORTED_ERR</a></code> exception and abort these steps.</p></li>
       <li><p>Let <var title="true">initDataFormat</var> be the container type specified by <var title="true">contentType</var>.</p></li>
@@ -475,7 +475,7 @@
     <p>The <dfn id="dom-loadsession"><code>loadSession(sessionId)</code></dfn> method must run the following steps:</p>
     <ol>
       <li><p>If the <a href="#cdm">content decryption module</a> corresponding to the <code><a href="#dom-keysystem">keySystem</a></code> attribute does not support loading previous sessions, throw a <code><a href="http://www.w3.org/TR/dom/#dom-domexception-not_supported_err">NOT_SUPPORTED_ERR</a></code> exception and abort these steps.</p></li>
-      <li><p>If <var title="true">sessionId</var> is null or an empty string, throw an <code><a href="http://www.w3.org/TR/dom/#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and abort these steps.</p></li>
+      <li><p>If <var title="true">sessionId</var> is an empty string, throw an <code><a href="http://www.w3.org/TR/dom/#dom-domexception-invalid_access_err">INVALID_ACCESS_ERR</a></code> exception and abort these steps.</p></li>
       <li>Let <var title="true">session</var> be a new <code><a href="#dom-mediakeysession">MediaKeySession</a></code> object, and initialize it as follows:
         <ol>
           <li><p>Set the <code><a href="#dom-error">error</a></code> attribute to null.</p></li>
@@ -563,9 +563,9 @@
     <p>It must run the following steps:</p>
     
     <ol>
-      <li><p>If <var title="true">keySystem</var> is null or an empty string, return false and abort these steps.</p></li>
+      <li><p>If <var title="true">keySystem</var> is an empty string, return false and abort these steps.</p></li>
       <li><p>If <var title="true">keySystem</var> contains an unrecognized or unsupported <a href="#key-system">Key System</a>, return false and abort these steps. Key system string comparison is case-sensitive.</p></li>
-      <li><p>If <var title="true">contentType</var> is null or an empty string, return true and abort these steps.</p></li>
+      <li><p>If <var title="true">contentType</var> was not provided or is an empty string, return true and abort these steps.</p></li>
       <li><p>If <var title="true">contentType</var> contains an invalid or unrecognized MIME type, return false and abort these steps.</p></li>
       <li><p>Let <var title="true">initDataFormat</var> be the container type specified by <var title="true">contentType</var>.</p></li>
       <li><p>If the user agent does not support the <a href="#initialization-data">Initialization Data</a> format <var title="true">initDataFormat</var>, return false and abort these steps.</p></li>

--- a/encrypted-media/encrypted-media.xml	Mon Mar 24 15:15:39 2014 -0700
+++ b/encrypted-media/encrypted-media.xml	Mon Mar 24 17:45:28 2014 -0700
@@ -345,7 +345,7 @@
     <p>The <dfn id="dom-mediakeys-constructor"><code>MediaKeys(<var title="true">keySystem</var>)</code></dfn> constructor must run the following steps:</p>
 
     <ol>
-      <li><p>If <var title="true">keySystem</var> is null or an empty string, throw an <invalid-access-err/> exception and abort these steps.</p></li>
+      <li><p>If <var title="true">keySystem</var> is an empty string, throw an <invalid-access-err/> exception and abort these steps.</p></li>
       <li><p>If <var title="true">keySystem</var> is not one of the user agent's supported <a href="#key-system">Key Systems</a>, throw a <not-supported-err/> and abort these steps. Key system string comparison is case-sensitive.</p></li>
       <li>Create a new <coderef>MediaKeys</coderef> object.
         <ol>
@@ -380,7 +380,7 @@
     </p>
 
     <ol>
-      <li><p>If <var title="true">contentType</var> is null or an empty string, throw an <invalid-access-err/> exception and abort these steps.</p></li>
+      <li><p>If <var title="true">contentType</var> is an empty string, throw an <invalid-access-err/> exception and abort these steps.</p></li>
       <li><p>If <var title="true">initData</var> is null or an empty array, throw an <invalid-access-err/> exception and abort these steps.</p></li>
       <li><p>If <var title="true">contentType</var> contains an invalid or unrecognized MIME type, throw a <not-supported-err/> exception and abort these steps.</p></li>
       <li><p>Let <var title="true">initDataFormat</var> be the container type specified by <var title="true">contentType</var>.</p></li>
@@ -464,7 +464,7 @@
     <p>The <methoddfn name="loadSession">loadSession(<var title="true">sessionId</var>)</methoddfn> method must run the following steps:</p>
     <ol>
       <li><p>If the <a href="#cdm">content decryption module</a> corresponding to the <coderef>keySystem</coderef> attribute does not support loading previous sessions, throw a <not-supported-err/> exception and abort these steps.</p></li>
-      <li><p>If <var title="true">sessionId</var> is null or an empty string, throw an <invalid-access-err/> exception and abort these steps.</p></li>
+      <li><p>If <var title="true">sessionId</var> is an empty string, throw an <invalid-access-err/> exception and abort these steps.</p></li>
       <li>Let <var title="true">session</var> be a new <coderef>MediaKeySession</coderef> object, and initialize it as follows:
         <ol>
           <li><p>Set the <coderef>error</coderef> attribute to null.</p></li>
@@ -546,9 +546,9 @@
     <p>It must run the following steps:</p>
     
     <ol>
-      <li><p>If <var title="true">keySystem</var> is null or an empty string, return false and abort these steps.</p></li>
+      <li><p>If <var title="true">keySystem</var> is an empty string, return false and abort these steps.</p></li>
       <li><p>If <var title="true">keySystem</var> contains an unrecognized or unsupported <a href="#key-system">Key System</a>, return false and abort these steps. Key system string comparison is case-sensitive.</p></li>
-      <li><p>If <var title="true">contentType</var> is null or an empty string, return true and abort these steps.</p></li>
+      <li><p>If <var title="true">contentType</var> was not provided or is an empty string, return true and abort these steps.</p></li>
       <li><p>If <var title="true">contentType</var> contains an invalid or unrecognized MIME type, return false and abort these steps.</p></li>
       <li><p>Let <var title="true">initDataFormat</var> be the container type specified by <var title="true">contentType</var>.</p></li>
       <li><p>If the user agent does not support the <a href="#initialization-data">Initialization Data</a> format <var title="true">initDataFormat</var>, return false and abort these steps.</p></li>