- Tests the presence of a connection. A PING message results in a PONG
- reply. If <server2> is specified, the message gets passed on to it.
+ Tests the presence of a connection to a client or server.
+ .
+ If no <target> has been given, the local server is used. User clients
+ can only use other servers as <target>, no user clients.
+ .
+ A PING message results in a PONG reply containing the <token>, which
+ can be arbitrary text.
+
+ Please note:
+ The RFCs state that the <token> parameter is used to specify the
+ origin of the PING command when forwared in the network, but this
+ is not the case: the sender is specified using the prefix as usual,
+ and the parameter is used to identify the PONG reply in practice.
+
+ References:
+ - RFC 2812, 3.7.2 "Ping message"