Many installable drivers process the second parameter of the DRV_OPEN message, giving the system and applications the means to send additional information to the driver when opening an instance.

• 很多可安装驱动程序都处理DRV_OPEN消息的第二个参数，在处理过程中，给与系统和应用程序在打开驱动实例时给驱动程序发送附加信息的手段。