ISO 10303规定了一种语言，通过该语言可以定义产品数据的各个方面。这种语言叫做表达。ISO 10303-11:20 04还规定了EXPRESS语言中构造子集的图形表示。这种图形表示称为EXPRESS-G。EXPRESS是ISO 10303-1中定义的数据规范语言。它由语言元素组成，允许明确的数据定义和对所定义数据的约束规范。 以下内容属于ISO 10303-11:20 04的范围: 数据类型；对数据类型实例的约束。 以下内容超出了ISO 10303本部分的范围: 数据库格式的定义；文件格式的定义；传输格式的定义；过程控制；信息处理；异常处理。 EXPRESS不是编程语言。

ISO 10303 specifies a language by which aspects of product data can be defined. The language is called EXPRESS. ISO 10303-11:2004 also specifies a graphical representation for a subset of the constructs in the EXPRESS language. This graphical representation is called EXPRESS-G. EXPRESS is a data specification language as defined in ISO 10303-1. It consists of language elements that allow an unambiguous data definition and specification of constraints on the data defined. The following are within the scope of ISO 10303-11:2004:

• data types;
• constraints on instances of the data types.

The following are outside the scope of this part of ISO 10303:

• definition of database formats;
• definition of file formats;
• definition of transfer formats;
• process control;
• information processing;
• exception handling.

EXPRESS is not a programming language.