THROW without an Argument
Argumentless THROW re-signals the current system error, transferring control to the next exception handler. The current system error is the error referenced by the $ZERROR special variable. Thus, an argumentless THROW is equivalent to the command ZTRAP $ZERROR.
Use of argumentless THROW is not recommended, because which system error is the current system error may change. For instance, this would occur if the error handler changes the $ZERROR value, or if the error handler itself generates a system error. It is therefore preferable to explicitly specify the system error to be thrown to the next exception handler by using THROW oref.
