http://tools.ietf.org/html/rfc1459.html#section-5.8
The ISON command was implemented to provide a quick and efficient means to get a response about whether a given nickname was currently on IRC. ISON only takes one (1) parameter: a space-separated list of nicks. For each nickname in the list that is present, the server adds that to its reply string. Thus the reply string may return empty (none of the given nicks are present), an exact copy of the parameter string (all of them present) or as any other subset of the set of nicks given in the parameterThere's currently no way to find out whether a user is online or not without doing unnecessary things like sending WHOIS or !stat to BanchoBot, and that is why I'd like to see the said command implemented.