DATA

The DATA command is used for out-of-band data transfer. The payload or message may be interpreted according to the tag. If the tag is unknown, the message may be discarded.
Sending Data to a Target
Usage: DATA <target> <tag> :<message>
<target> The target of the data transfer (nickname or channel).
<tag> A tag indicating the format or type of the data.
<message> The data to be transferred.
Sending Data to Users in a Channel
Usage: DATA <channel> [<nicklist>] <tag> :<message>
<channel> The target channel.
<nicklist> A comma-separated list of target users in the channel.
<tag> A tag indicating the format or type of the data.
<message> The data to be transferred.

(See section 6.4 of IRCX)