|1||The server refnum is connected to irc and is using an SSL/TLS socket|
|0||Any other condition (refnum is invalid; not connected to that server; not using ssl with that server)|
Since 0 can mean several things, you can use serverctl to see if a refnum is invalid, or if the server is not connected yet.
This function was part of EPIC-SSL. It first appeared in EPIC4-1.1.3