question: public boolean isExistingCommand ( ) { return ( ! name . equals ( CommandTagHandle . CMD_UNKNOWN ) ) ; }
target:  Check whether the present CommandTagHandle object represents a CommandTag that exists on the server. If not, the client will not be able to  execute the command. Preferably, clients should check isExistingCommand() BEFORE they call the setValue() method. If the command doesn't exist, setValue() will throw a CommandTagValueException.