The motivation is to avoid "flag" values such as -1 and 99999 which will distort the true range of values.
其目的是为了避免像 -1 和 99999 这样的“标志”值，以免它们扭曲真正的取值范围。
2
The only part remaining is the handling of error reporting (such as an unknown parameter flag character or a numeric value out of range).
最后剩下的部分就是处理错误报告（例如一个未知的形参标记字符或者一个超出范围的数字值）。
3
This flag requires the user specify the maximum allowable connections for the current policy, the start port, and the end port (can be the same as start port if not specifying a port-range).