在http://www.unix.org/version3/注册也可以下载。 对操作系统编写人员有用： The Single UNIX Specification Version 3 - incorporating IEEE Std 1003.1 and ISO/IEC 9945 and integrating the industry's Open Systems standards. Press Release Overview Paper ISO/IEC 9945:2003 IEEE S
Single sign-on (SSO) is a property of access control of multiple related, but independent software systems. With this property a user logs in once and gains access to all systems without being prompted to log in again at each them.
