+ The <founder auth> is Authentication Payload providing the
+ authentication for gaining founder privileges on the channel
+ when joining the channel. The client may provide this if it
+ knows that it is the founder of the channel and that the
+ SILC_CMODE_FOUNDER_AUTH mode is set on the channel. The server
+ MUST verify whether the client is able to gain the founder
+ privileges the same way as the client had given the
+ SILC_COMMAND_CUMODE command to gain founder privileges. The
+ client is still able to join the channel even if the founder
+ privileges could not be gained. If the channel is invite only
+ channel, the client is able to join the channel only if it
+ was invited to the channel or was able to gain the founder
+ privileges.
+