Introduction

ISO 10303 is an International Standard for the computer-interpretable representation of product information and for the exchange of product data. The objective is to provide a neutral mechanism capable of describing products throughout their life cycle. This mechanism is suitable not only for neutral file exchange, but also as a basis for implementing and sharing product databases, and as a basis for retention and archiving.

This part of ISO 10303 specifies an application module for the representation of various breakdowns of products. A breakdown is a partitioning of a product into a set of related elements to support engineering, analysis and other activities that can be performed in relation to the product.

The exact nature of a breakdown is determined by three different aspects of the breakdown:

• The items that constitute the nodes or elements in the breakdown, including whether these are heterogeneous or homogeneous;
• The interpretation placed on the relationships between the elements in the breakdown;
• The rule set being followed by the creator of the breakdown.

This module does not place any constraints on these three aspects. However, there are specific types of breakdowns defined in other modules that specialise the entities provided in this module. These breakdowns are explicit, parent-child views that are constrained to use homogeneous elements and therefore provide specific breakdown types:

• functional [5];
• physical [4];
• system [3];
• zonal [6].

A breakdown can be asserted to be a Hybrid breakdown using the specialization described in [7]. Such a breakdown uses heterogeneous elements.

These views are complementary to the assembly structure and bill of materials views that are the primary focus for manufacturing (realization) of a product [2]. Product breakdowns differ from such assembly structures in that the relationships between the nodes are often specific to both the particular breakdown and the product or products to which the breakdown applies. In the case of an assembly structure the meaning of the relationships between components is always a variant of the idea of assembly and so any sub-tree can be used in multiple assemblies. A similar sub-tree of a product breakdown can only be applicable to the breakdown of the product in which it is defined. The extent to which this is the case depends on the rule set followed by the creator of the breakdown.

Breakdowns can be of designs or realized individual products. For example, the functional breakdown of an individual product that has been damaged will be different to the functional breakdown of the design of that product type. For any product, more than one breakdown can exist to support various different engineering activities.

A Breakdown is a type of Product and, thus, has identification and can have versions (Breakdown_version).

Each version of a breakdown (Breakdown_version) is related to the product that is the subject of the breakdown through Breakdown_of.

The constituents of a breakdown are represented by Breakdown_element objects.

A Breakdown_element can appear in one or more breakdowns and is a Product with identification, versions (Breakdown_element_version) and views (Breakdown_element_definition) of those versions.

A Breakdown_element_usage identifies the parent-child relationship between a pair of Breakdown_element objects in the context of the relevant breakdown. The complete breakdown hierarchy consists of a tree of Breakdown_element_usage objects.

A Breakdown_element can be one of the allowed subtypes:

• a Functional_element (see in [5]);
• a Physical_element (see in [4]);
• a System_element (see in [3]);
• or a Zone_element (see in [6]).

Other types of element can be introduced by classification of the Breakdown_element entity. The nature of the relationship between elements in the breakdown can also be refined by means of classification.

This part of 10303 also supports the requirement to identify the product or relationship between products that is the realization of a Breakdown_element_definition or a Breakdown_element_usage. A Breakdown_element_realization provides this identification.

Clause 1 defines the scope of the application module and summarizes the functionality and data covered. Clause 3 lists the words defined in this part of ISO 10303 and gives pointers to words defined elsewhere. The information requirements of the application are specified in Clause 4 using terminology appropriate to the application. A graphical representation of the information requirements, referred to as the application reference model, is given in Annex C. Resource constructs are interpreted to meet the information requirements. This interpretation produces the module interpreted model (MIM). This interpretation, given in 5.1, shows the correspondence between the information requirements and the MIM. The short listing of the MIM specifies the interface to the resources and is given in 5.2. A graphical representation of the short listing of the MIM is given in Annex D.

In ISO 10303, the same English language words can be used to refer to an object in the real world or concept, and as the name of an EXPRESS data type that represents this object or concept.

The following typographical convention is used to distinguish between these. If a word or phrase occurs in the same typeface as narrative text, the referent is the object or concept. If the word or phrase occurs in a bold typeface or as a hyperlink, the referent is the EXPRESS data type.

The name of an EXPRESS data type can be used to refer to the data type itself, or to an instance of the data type. The distinction between these uses is normally clear from the context. If there is a likelihood of ambiguity, either the phrase "entity data type" or "instance(s) of" is included in the text.

Double quotation marks " " denote quoted text. Single quotation marks ' ' denote particular text string values.

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