Note that extensions to the directory protocol should begin their item keywords with "x-" or "X-".
svn:r10108
Implementations MUST prefix items not recognized by older versions of Tor
with an "opt" until those versions of Tor are obsolete.
+ Other implementations that want to extend Tor's directory format MAY
+ introduce their own items. The keywords for extension items SHOULD start
+ with the characters "x-" or "X-", to guarantee that they will not conflict
+ with keywords used by future versions of Tor.
+
2. Router operation
ORs SHOULD generate a new router descriptor whenever any of the