$(...)

This identifier allows you to create a dynamic match parameter in an event.

$(...)

You can use $1- to reference the incoming line.

Note that this identifier can only be used in a match text of an event.

Example

On *:TEXT:$(* $+ $me $+ *):#: {
 echo -a $nick just mentioned your nickname in $chan $+ .
}

This example will echo to your active window whenever someone mentioned your nickname.