TAGMSG

The TAGMSG command is used to send tagged messages to other users or channels without a message body.

Sending a Tagged Message
Usage: <tags> TAGMSG <target>
<tags> Message tags prefixed to the command.
<target> The target user or channel to send the tagged message to.

Sending a Tagged Message to Members of a Channel
Usage: <tags> TAGMSG <channel> [<nicklist>]
<tags> Message tags prefixed to the command.
<channel> The channel to send the tagged message to.
<nicklist> (Optional) A comma-separated list of nicknames to send the tagged message to.

This command functions similarly to PRIVMSG, but without a message body. It allows sending messages with associated metadata via tags. When sending messages to users on a channel using a nicklist, the targeted users will not receive a list of other recipients.

(See section Message Tags of IRCv3)