PDM-UG: Product Context Information
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This page belongs to the PDM Usage Guide.
Context information provides a scope and necessary circumstance for product identification information. It consists of two separate and related areas:
- Application Protocol Identification,
- Application Context Information.
Application Protocol identification is provided by the entity application_protocol_definition. It characterizes the STEP Application Protocol (AP) or similar working draft STEP specification that includes or uses the PDM Schema and provides the scope or general context for the exchange data set. The general context identifies the usage of the information within the scope of the PDM Schema, and may define the application domain which provides a basis for the interpretation of all information represented in the product data exchange. It is generally recommended that application protocol identification and general context information be handled structurally the same for 'Part as Product' and 'Document as Product' as for 'Product Concept'. A single instance of the entity application_context is typically referenced by all product_context and product_concept_context entities. This application_context instance is referenced by a single instance of the entity application_protocol_definition.
Application context information identifies the usage of the information within the scope of the PDM Schema. Application context information is divided into application domain information and product definition context information:
- The application domain is identified by the application_context entity. Each application domain is represented by an instance of application_context that is referenced by product view definitions (product view and type definition) which belong to the application domain;
- The product_definition_context carries information distinguishing the life-cycle stage (e.g., design, manufacturing) relevant to a particular product view definition as well as indication of the type of the definition - e.g., part definition, functional definition.
Identification of a valid scope and context of interpretation for the identifier of a product is also required in the PDM Schema. This involves the assignment of an organization to the product, in the role 'id owner' to identify the scope of uniqueness and validity of the product id.
The Instance Model: EXPRESS entities and attributes
The EXPRESS entities and attributes used to support the requirements of context information related to basic product identification are illustrated in Diagram 2 below. The corresponding STEP exchange file encoding is illustrated in Example 2.
Application protocol definition
The application_protocol_definition entity represents the identification of the STEP Application Protocol (AP) that specifies the scope and extent of the application domain appropriate for this information model. An AP that uses the PDM Schema should provide values for the attributes of this entity.
Attributes
- The application_interpreted_model_schema_name attribute identifies the name of the EXPRESS schema that specifies the information model used for the data representation and exchange.
- The application_protocol_year attribute identifies the year of publication of the specification.
- The status attribute provides information about the degree of maturity of the defining specification.
- The applications attribute provides a reference to the associated application_context entity.
| ENTITY application_protocol_definition | Attribute Population | Remarks |
| application_interpreted_model_schema_name | type: label = text 'pdm_schema' | If the PDM Schema is contained within an Application Protocol, the AP name should be used. |
| application_protocol_year | type: year_number = integer 2000 | If the PDM Schema is contained within an Application Protocol, the AP year should be used. |
| status | type: label = text 'version 1.2' | If the PDM Schema is contained within an Application Protocol, the AP status should be used. |
| applications | type: entity = application_-context |
===Preprocessor Recommendations=== This entity should be instantiated exactly once in the data set. In some cases, an application protocol may support multiple application_contexts. The entity application_protocol_definition should reference the 'primary' defining application context for the product data that is being exchanged.
===Postprocessor Recommendations=== There are no specific postprocessor recommendations.
===Related Entities=== There are no specific related entities.
Application context
The application_context entity identifies the application domain that defined the data. The application_context entity may have an identifier associated with it through the entity id_attribute and its attribute_value attribute. The application_context entity may have a description associated with it through the entity description_attribute via the attribute attribute_value. It is not recommended to instantiate these optional values.
In the case of application protocol identification the application domain is optional, which provides a basis for the interpretation of all information represented in the product data exchange.
In the case of application context information, there exists a 'primary' application context for each product_definition. This is the value of the attribute product_definition.frame_of_reference; it is the frame_of_reference for the 'primary' product_definintion_context (see product_definition_context). This 'primary' application context represents the defining application domain for each product_definition. Additional application domains may be associated with a product_definition through additional product_definition_contexts via the entity product_definition_context_association.
Attributes
- The application attribute identifies the name of the general application domain that defined the data.
| ENTITY application_context | Attribute Population | Remarks |
| application | type: label = text |
===Preprocessor Recommendations=== This entity should be instantiated once in the data set for each relevant application domain. There is no standard mapping for the application attribute of application_context in the case of application protocol identification. Therefore application domain is optional in this case.
Where appropriate, the value 'assembly study', 'digital mock up', 'process planning', 'electrical design', or 'mechanical design' should be used.
NOTE - 'electrical design' and 'mechanical design' are not understood to mean the design life cycle - e.g., within the application domain 'mechanical design', you may have concurrent 'manufacturing' and 'design' life-cycle view definitions.
===Postprocessor Recommendations=== There are no specific postprocessor recommendations.
===Related Entities=== There are no specific related entities.
Product context
The product_context entity is a subtype of application_context_element. All STEP products must be founded in a product_context to specify the point of view on the application. The product_context entity identifies the engineering discipline's point of view from which the data is being presented. This entity will establish the context perspective and source of requirements for product entities (see product).
Attributes
- The discipline_type attribute contains a description of the discipline point of view for a product.
| ENTITY product_context | Attribute Population | Remarks |
| name | type: label = text | |
| frame_of_reference | type: entity = application_context | |
| discipline_type | type: label = text |
===Preprocessor Recommendations=== It is recommended to instantiate this entity exactly once in the data set. There is no standard mapping for the name attribute of a product_context. There is no standard mapping for the discipline_type attribute.
===Postprocessor Recommendations=== Past use of the attribute discipline_type may result in values such as 'mechanical' or 'electrical'.
===Related Entities=== There are no specific related entities.
Product definition context
The product_definition_context entity is a subtype of application_context_element. All STEP product_definitions must be founded in a product_definition_context to identify the product definition type and life-cycle stage from which the data is viewed.
There are two ways to implement the product_definition_context in STEP:
- association of a single primary context with a product_definition,
- assignment of more than one (additional) context to a product_definition.
The value of the attribute product_definition.frame_of_reference is a product_definition_context that represents the 'primary' defining context for a view. In general this defining context is qualified both by type (product_definition_context.name) and by life-cycle (product_definition_context.life_cycle_stage) information. The primary context also has associated application domain information (see application_context).
The product_definition_context_association entity allows for multiple additional contexts to be associated with a single product_definition. There is always one required 'primary' context that identifies the defining application domain and life-cycle information. Additional product_definition_context entities identify additional concurrent relevant views on the product_definition. These application_contexts are related to the product definition by product_definition_context_association.
Attributes
- The name attribute indicates the type of view being defined.
- The frame_of_reference attribute is a pointer to the associated application_context entity.
- The life_cycle_stage attribute identifies the life-cycle view on the associated product_definition.
| ENTITY product_definition_context | Attribute Population | Remarks |
| name | type: label = text | Distinguishes the type of the associated product_definition |
| frame_of_reference | type: entity = application_context | |
| life_cycle_stage | type: label = text | string appropriate to describe the life-cycle point of view |
===Preprocessor Recommendations=== The name attribute provides a distinction on the type of view on a part version ('part definition') from one of a document version ('digital document definition', 'physical document definition'). This attribute may also indicate other types of definitions: e.g., functional, or spatial and/or zonal.
The attribute life_cycle_stage contains a description of the particular viewpoint from which the data may be interpreted. Recommended values include 'design' and 'manufacturing'. Preprocessors should identify life-cycle information for the defining 'primary' product_definition_context, they may also indicate additional relevant life_cycle_stage information with a second product_definition_context, related via the product_definition_context_association
===Postprocessor Recommendations=== Postprocessors should interpret the value of the name attribute as a type distinction between various definitions of parts and documents. The life_cycle_stage attribute value may be interpreted as the relevant viewpoint from which the data is valid. Interoperable processors will understand life-cycle information from the defining 'primary' product_definition_context as well as any additional life-cycle information provided by other relevant product_definition_context entities related via the product_definition_context_association. The product_definition_context_association entity may or may not be present relating a product_definition with the 'primary' context information.
===Related Entities=== There are no specific related entities.
Product definition context association
The product_definition_context_association entity allows for multiple additional contexts to be associated with a single product_definition.
With 'Part as Product', there is always one required 'primary' context that identifies the defining application domain and life-cycle information from which the data is viewed. This 'primary' context is the value of the attribute product_definition.frame_of_reference. Additional product_definition_context entities identify additional concurrent relevant views on the product_definition. These additional contexts are related to the product definition by the entity product_definition_context_association.
Attributes
- The definition attribute provides a reference to the associated product_definition entity.
- The frame_of_reference attribute is a pointer to the associated product_definition_context entity.
- The role attribute gives an optional role indication to the association.
| ENTITY product_definition_context_association | Attribute Population | Remarks |
| definition | type: entity = product_definition | |
| frame_of_reference | type: entity = product_definition_context | |
| role | type: entity = product_definition_context_role |
===Preprocessor Recommendations=== There are no specific preprocessor recommendations
===Postprocessor Recommendations=== Interoperable postprocessors should expect that a product_definition_context_association entity might be, or might not be, present to relate a product_definition with its 'primary' context information.
===Related Entities=== There are no specific related entities.
Product definition context role
The product_definition_context_role entity provides a role string that is related to a product_definition_context_association entity.
Attributes
- The name attribute provides the word or group of words by which the role is referred.
- The description attribute provides additional descriptive information related to the role.
| ENTITY product_definition_context_role | Attribute Population | Remarks |
| name | type: label = string | 'additional context' |
| description | type: text = string | OPTIONAL |
===Preprocessor Recommendations=== There are no specific preprocessor recommendations.
===Postprocessor Recommendations=== There are no specific postprocessor recommendations.
===Related Entities=== There are no specific related entities.
The Instance Model: STEP exchange file format (ISO10303 Part 21 syntax)
#10 = APPLICATION_PROTOCOL_DEFINITION('version 1.2','pdm_schema',2000, #20);
#20 = APPLICATION_CONTEXT('mechanical design');
#30 = PRODUCT_CONTEXT('', #20, '');
#40 = PRODUCT('part_id', 'part_name', 'part_description', (#30));
#60 = PRODUCT_DEFINITION_FORMATION('pversion_id','pversion_desc',#40);
#80 = PRODUCT_DEFINITION('view_id', 'view_name', #60, #90);
#90 = PRODUCT_DEFINITION_CONTEXT('part definition', #20, );
#10 = APPLICATION_PROTOCOL_DEFINITION('version 1.2','pdm_schema',2000, #20);
#20 = APPLICATION_CONTEXT();
#30 = PRODUCT_CONTEXT('', #20, '');
#40 = PRODUCT('part_id', 'part_name', 'part_description', (#30));
#60 = PRODUCT_DEFINITION_FORMATION('pversion_id','pversion_desc',#40);
#80 = PRODUCT_DEFINITION('view_id', 'view_name', #60, #90);
#90 = PRODUCT_DEFINITION_CONTEXT('part definition', #100, 'design');
#100 = APPLICATION_CONTEXT('mechanical design');
#110 = PRODUCT_DEFINITION_CONTEXT_ASSOCIATION (#80, #130, #120);
#120 = PRODUCT_DEFINITION_CONTEXT_ROLE ('additional context', $);
#130 = PRODUCT_DEFINITION_CONTEXT('', #100, 'manufacturing');
