[Link] is a command that hosts can use to make a topic appear in more than one conference. The host selects what other conference to link the topic to, clicks a confirmation, and then a copy appears there. The system automatically puts a note in the topic so that people know it is now linked.
Note that this is different from the way linking works in picospan and yapp. In those systems, the host of the destination conference does a "link from" command, grabbing the topic from the other conference. Here the host of the originating conference does a "link to", giving the topic to the new conference.