本补充文件扩展了子STS-1接口的范围，包括VT组的倍数有效载荷。具体而言，应允许N x VT组的子STS-1有效载荷，包括N=1-5。无论使用的N值是多少，都会使用相同的单列架空线路。

This supplement expands the range of sub STS-1 interfaces to include payloads that are multiples of the VT Group. Specifically, sub STS-1 payloads of N x VT Group shall be allowed with N = 1-5 inclusive. The same single column of Line overhead is used regardless of the value of N that is used.