本文件提供了一份经授权的替代金属材料规范和标准清单，用于撤销、废弃或部分取代的英国标准（BS）航空航天和通用工程以及国防部技术发展理事会（DTD）系列材料规范，参考AGS和AS系列中的ADS标准零件图纸。

This document provides a list of authorized alternative metallic material specifications and standards for withdrawn, obsolescent or partially superseded British Standard (BS) Aerospace and General Engineering and MoD Directorate of Technical Development (DTD) series material specifications referenced on ADS Standard Parts drawings in the AGS and AS series.