diff --git a/handbook/essentials_make.html b/handbook/essentials_make.html
index 27adae236..84e0a8f8a 100644
--- a/handbook/essentials_make.html
+++ b/handbook/essentials_make.html
@@ -31,6 +31,8 @@ both of which are stored in the <var>:loser:</var> repository in :loser:/gpx/ .
 <p>Read the <a href="troggle/make-essentialsREADME.txt">README</a> file in that directory.
 <p>They are documented in the long list of <a href="troggle/scriptsother.html">Other scripts</a>.
  
+  <h3>The "undescended shafts" GPX files</h3>
+This can be generated and downloaded by any web user on the page <a href=" /caves_undropped">undropped caves</a> page. A copy is manually (infrequently) copied to <var>expofiles</var> at <a href="/expofiles/gpslogs/essentials/undropped.gpx" download>gpslogs/essentials/undropped.gpx</a>.
    <hr />
 
 <a href="/handbook/computing/myphone.html">Your phone on expo</a> - Do not select the "high accuracy" location setting on your phone<br />