A cryptic comment in dir-spec.txt is now a complete proposal.

svn:r17452

doc/spec/dir-spec.txt

@@ -1519,7 +1519,6 @@ $Id$
    The key certificate whose signing key fingerprint is <F> should be
    available at:
       http://<hostname>/tor/keys/sk/<F>.z
-   [XXX020 cross-certify?]
 
    The most recent descriptor for a server whose identity key has a
    fingerprint of <F> should be available at: