The getmembersonline command returns a CSV list of agent names that are reported to be offline in the specified group.

llInstantMessage(CORRADE,
    wasKeyValueEncode(
        [
            "command", "getmembersoffline",
            "group", wasURLEscape(GROUP),
            "password", wasURLEscape(PASSWORD),
            "callback", wasURLEscape(URL)
        ]
    )
);

• The command is similar to the getmembers command, except that the output returns only offline members.
• This command is a convenience function that returns resolved agent names - if UUIDs are desired, then the getgroupmembersdata command whilst filtering by OnlineStatus using sifting may be preferable.
• The output may be very large and the command may take some time to complete (or even timeout). In which case, Corrade's internal HTTP server can be used to obtain large results.
• In order to retrieve online members, the getmembersonline command can be used.