diff --git a/doc/dir-spec.txt b/doc/dir-spec.txt
index 3cd8d0bbb3..0a1547687d 100644
--- a/doc/dir-spec.txt
+++ b/doc/dir-spec.txt
@@ -331,7 +331,10 @@ $Id$
 
    The most recent descriptor for this server should be at:
       http://<hostname>/tor/server/authority.z
-    [Nothing in Tor uses this resource but it is at times handy for debugging.]
+    [Nothing in the Tor protocol uses this resource yet, but it is useful
+     for debugging purposes. Also, the official Tor implementations
+     (starting at 0.1.1.x) use this resource to test whether a server's
+     own DirPort is reachable.]
 
    A concatenated set of the most recent descriptors for all known servers
    should be available at: