说明：  NASA开发的软件度量手册，可以作为SQA软件度量方面的系统学习和全面参考。没有找到更新的版本，诸位牛牛先将就用用。
(NASA developed software metrics manuals, software metrics can be used as SQA systematic and comprehensive study and reference. Did not find a newer version, you first used by Niuniu.)