该文档里面详细说明了USB设备标准请求的格式及各类请求的编号,同时详细解释了所有的标准请求,还包含了常用的描述符的格式及各字段详细说明,额外增加了HID描述符等(The document details the format of the USB device standard request and the number of various requests, and explains all the standard requests in detail. It also includes the format of the commonly used descr iptors and detailed descr iption of each field, and adds the HID descr iptor and so on)