diff --git a/docs/formats.html b/docs/formats.html
index cac1788..3eb76b2 100644
--- a/docs/formats.html
+++ b/docs/formats.html
@@ -589,6 +589,11 @@ In input, the next byte or bytes must match the checksum.
    href="http://www.ietf.org/rfc/rfc1950.txt">RFC 1950</a>.</dd>
  <dt><code>%&lt;hexsum8&gt;</code></dt>
   <dd>One byte. The sum of all hex digits. (Other characters are ignored.)</dd>
+ <dt><code>%&lt;lrc&gt;</code></dt>
+  <dd>One byte. The Longitudinal Redundancy Check according to <a target="ex"
+   href="https://en.wikipedia.org/wiki/Longitudinal_redundancy_check">Wikipedia</a>.</dd>
+ <dt><code>%&lt;hexlrc&gt;</code></dt>
+  <dd>One byte. The LRC for the hex digits. (Other characters are ignored.)</dd>
 </dl>
 
 <a name="regex"></a>