With the VCE_ifValue event, it sends the output to the brick. <var:cl:Test> would check the Clients variable Test, check for whatever you have after that, then send the output to the brick
Ex;
onActivate -> self -> VCE_ifValue -> <var:client:lastMsg> -> Equals -> Hello!
onVariableTrue -> client -> centerPrnt -> You said Hello!
You can change the Self to a other named brick and the onVariableTrue would have to be on that said named brick.