canSubstitute                                 (Assignable)

        Contains a logical value indicating whether a new result can be
        substituted for the operation that produced the error condition.
        Argument errors and certain other simple errors allow the error
        handler to substitute a new result value for the failed operation.  A
        value of true (.T.) means that substitution is possible.

        The substitution is performed by returning the new result value from
        the code block invoked to handle the error.  Note that
        Error:canSubstitute is never true (.T.) if either Error:canDefault or
        Error:canRetry is true (.T.).