Introduction

ISO 10303-239 (PLCS) specifies an information model that defines what information can be exchanged and represented to support a product through life. This definition is achieved using the EXPRESS information modelling language.

The basic data structures that are exchanged are defined by EXPRESS Entities. For example in PLCS there are entities defining Parts, versions of parts (Part_versions) people (Person). Each entity may have attributes that provide further information about the thing being represented by an entity. For example, a person has a first name and last name. These are attributes of a Person.

The information model defined by ISO 10303-239 (PLCS) has a scope that is wider than most applications or any single data exchange. So it is unlikely that any piece of software will be able to declare compliance to PLCS as PLCS covers more than the software can handle. It is also going to be difficult to contract for data to be provided according to ISO 10303-239 as the scope is so large.

The DEXs (Data EXchange Set) aim to address this problem by providing a way of narrowing down the scope of the information model to be used in any given exchange.

In addition to narrowing the scope of information exchanged, the DEXs aim to provide usage guidance as to how the entitles should be used.

There are a number of parts of the PLCS model that will be common to many DEXs. (e.g. date and time). Rather than each DEX replicating the usage guidance for these, they are packaged into chapters called "Capabilities" that are reused across different DEXs. So a DEX is constructed from a set of capabilities and each capability describes the set of PLCS entities that are required to represent a particular concept.

As DEX reuses capabilities different interpretations of equivalent concepts in different DEXs are avoided.

The information model defined by ISO 10303-239 (PLCS) is quite generic. It hold no business specific terms, which means that the model enteties in some way must achive this semantic. This is done through classification with so called Reference data.

In summary:

• A DEX defines a subset of the ISO 10303-239 (PLCS) information model against which software can claim conformance and data exchange contracts can be written.
• A DEX uses capabilities to provide guidance on how the information model should be used. In other capabilities words describes how the entities are to be used to represent a given concept.
• Entities are the atomic structures that are used to define PLCS.
• Reference data adds business specific semantics to the entities.

DEX architecture

The DEX architecture is shown in Figure 1, and comprises:

• DEX Specifications;
• Capabilities;
• Business concepts;
• Reference data;
• Data Exchange agreements.

These are described in the following sections.

Conventions in DEXlib

Reference data

Model diagrams

Instance diagrams

Instance diagrams shows instances (denoted by the lower-right triangle with instance number, for example '#510') of EXPRESS entities. Each rectangular box denotes an instance of an entity. The lines between the boxes represent attributes which form relationships from one to the other (in the direction of the line ending in a small open circle ---o). Some entities are abstract and are only instantiated through their subtypes, which inherit any attributes present in the supertype. On the diagram, this is indicated by supertype=> i.e. the name of the supertype followed by the symbols = and >. The name of the subtype instantiated has no symbols following the name. The basic attributes shown are in italic font in the format attribute name=value where the name of the attribute is followed by it's value. An empty string is denoted by single quote marks ' ', while an un-populated attribute is denoted by the symbol $.

Relationship to PDM Schema