谁明白这幅图的意思?2000DDK文档

For example, consider a device that supports a configuration with two interfaces, and the first interface supports two alternate settings. The configuration information is laid out in memory as follows:



Figure 2.1 Example of Configuration Descriptor Layout

这幅图中是不是有错误?
它说有两个Interface,第一个interface有两个Alternate setting.但我看图上,只画了一个interface, 而且前两个一样,后两个一样!
另外,endpoint 放在中间是什么意思?虚线什么意思?