说明：  UML参考手册 .一本软件系统人员的参考书。书中对UML的概念和组成做了详细介绍，包括其语义、语法、表示法和用途。对广大专业软件开发人员来说，这是一本使用方便、内容全面的参考书。
(UML Reference Manual. A software system of the reference staff. UML book on the concept and composition make a detailed introduction, including its semantics, grammar, expression and uses. Large numbers of professional software developers, this is an easy to use, comprehensive reference book.)