diff --git a/syntax/index.html b/syntax/index.html
index 37826b94..2d5c958b 100644
--- a/syntax/index.html
+++ b/syntax/index.html
@@ -853,6 +853,7 @@ <h3>Formats for dates and times</h3>
             The following time formats MUST be recognized by implementations:
           </p>
           <ul>
+            <li><code>HH:mm:ss.S</code> with one or more trailing <code>S</code> characters indicating the maximum number of fractional seconds e.g., <code>HH:mm:ss.SSS</code> for <code>15:02:37.143</code></li>
             <li><code>HH:mm:ss</code> e.g., <code>15:02:37</code></li>
             <li><code>HHmmss</code> e.g., <code>150237</code></li>
             <li><code>HH:mm</code> e.g., <code>15:02</code></li>
@@ -862,6 +863,7 @@ <h3>Formats for dates and times</h3>
             The following date/time formats MUST be recognized by implementations:
           </p>
           <ul>
+            <li><code>yyyy-MM-ddTHH:mm:ss.S</code> with one or more trailing <code>S</code> characters indicating the maximum number of fractional seconds e.g., <code>yyyy-MM-ddTHH:mm:ss.SSS</code> for <code>2015-03-15T15:02:37.143</code></li>
             <li><code>yyyy-MM-ddTHH:mm:ss</code> e.g., <code>2015-03-15T15:02:37</code></li>
             <li><code>yyyy-MM-ddTHH:mm</code> e.g., <code>2015-03-15T15:02</code></li>
             <li>any of the date formats above, followed by a single space, followed by any of the time formats above, e.g., <code>M/d/yyyy HH:mm</code> for <code>3/22/2015 15:02</code> or <code>dd.MM.yyyy HH:mm:ss</code> for <code>22.03.2015 15:02:37</code></li>