EXPRESS (data modeling language)

For formal verification and as input for tools such as SDAI the textual representation within an ASCII file is the most important one.

The graphical representation, called EXPRESS-G, is not able to represent all details that can be formulated in the textual form.

A main feature of EXPRESS is the possibility to formally validate a population of datatypes - this is to check for all the structural and algorithmic rules.

[4] It is a companion to the EXPRESS language for displaying entity and type definitions, relationships and cardinality.

One of the advantages of using EXPRESS-G over EXPRESS is that the structure of a data model can be presented in a more understandable manner.

The data model presented in figure could be used to specify the requirements of a database for an audio compact disc (CD) collection.

Since Person is declared to be ABSTRACT only occurrences of either (ONEOF) the subtype Male or Female can exist.

To restrict the possible combinations special supertype constraints got introduced such as ONEOF and TOTALOVER.

The functions and procedures allow formulating complex statements with local variables, parameters and constants - very similar to a programming language.

More details on the given examples can be found in ISO 10303-41 This article incorporates public domain material from the National Institute of Standards and Technology