PDM-UG: Relationships between document representations
From WikiSTEP
This page belongs to the PDM Usage Guide.
Product_definition_relationship associates, in the given context, two instances of product_definition that model a representation of a document. The semantics of the relationship are defined by the attributes name and description of the entity product_definition_relationship. The name attribute of product_definition_relationship defines the relation type.
Contents |
The Instance Model: EXPRESS entities and attributes
The figure below shows the general structure to link two product_definitions that model document representations. The semantics of the relation is defined by the string provided in product_definition_relationship.name.
Diagram 50: document representation relationship Instance Diagram
Product definition relationship
Attributes
- The id is an identifier that distinguishes the product_definition_relationship.
- The name is the label by which the product_definition_relationship is known.
- The description is an optional text that characterizes the product_definition_relationship.
- The relating_product_definition contains one of the product_definition entity types, which is a part of the relationship.
- The related_product_definition is the other product_definition, which is part of the relationship. If one attribute is dependent upon the other, this attribute shall be the dependent one.
| ENTITY product_definition_relationship | Attribute Population | Remarks |
| id | type: identifier = string | should be instantiated as |
| name | type: label = string | defines the semantics of the relation (see table below) |
| description | type: text = string | OPTIONAL |
| relating_product_definition | entity: product_definition | |
| related_product_definition | entity: product_definition |
===Preprocessor Recommendations=== None specified.
===Postprocessor Recommendations=== None specified.
===Related Entities=== the usage of product_definition_relationship described here relates two product_definitions that define document representations.
Where applicable the following values shall be used for product_definition_relationship.name:
- 'addition': specifies that the related document provides supplementary or collateral information with regard to the information provided by the relating document;
- 'copy': defines a relationship where the related document representation is a copy of the relating document representation;
- 'derivation': defines a relationship where the related document representation is derived from the relating document representation (e.g., a raster image may be derived from a 3D CAD model);
- 'decomposition': defines a relationship where the related document representation is one of potentially more sub documents of the relating document representation (e.g., a decomposition of a document into clauses or into several CAD models);
- 'peer': specifies that the related document provides required information with regard to that provided by the relating document. The peer document is essential for a complete understanding;
- 'reference': defines a relationship where the related document is referenced from the relating, e.g., a text processor representation referencing a CGM representation for inclusion as a graphical object in the text document;
- 'sequence': defines a logical sequence where the related document representation comes after the relating document representation (e.g., a sequence of clauses);
- 'substitution': defines a relationship where the related document representation replaces the relating document representation;
- 'translation': specifies that the related product_definition (document) was generated from the relating product_definition (document) with the intent to convey exactly the same information.
Examples: a ‘translation’ can geometry data from one system and presenting in an another systems, such as using Unigraphics geometry data and ‘translating’ in into another format, such as CATIA geometry data. The intent would be to make the geometry shape as close to the same as possible. A ‘translation’ can apply to other types of data as well. A standards document can be produced in WordPerfect and ‘translated’ to a pdf format. The intent is to keep the printable or viewable image of the document exactly the same in both file formats.
The relation types 'decomposition' and 'substitution' can be used to model 'assembly'-type structures of document representations. This approach does not mirror the approach taken with assembly_component_usage for the product structure. This reflects the understanding that there is no common requirement to manage document representation structures in the same way as product structure.
The Instance Model: STEP exchange file format (ISO10303 Part 21 syntax)
ISO-10303-21;
HEADER;
FILE_DESCRIPTION(('example for document rep structures'), '2;1');
FILE_NAME('', '20.08.1999, 10:16:08', ('n.n.'), (''), '', '', '');
FILE_SCHEMA(('PDM_SCHEMA {1.2}'));
ENDSEC;
DATA;
/* Entities #10 to #60 define the meta data for a managed document */
#10 = PRODUCT_DEFINITION_FORMATION('1', '', #20);
#20 = PRODUCT('d1', 'doc1', 'document nr 1', (#40));
#30 = PRODUCT_RELATED_PRODUCT_CATEGORY('document', '', (#20));
#40 = PRODUCT_CONTEXT('', #50, '');
#50 = APPLICATION_CONTEXT('');
#60 = APPLICATION_PROTOCOL_DEFINITION('version 1.2', 'pdm_schema', 2000, #50);
/* Entities #70 to #90 defines two digital files. The digital file #70 */
/* represents a text processor file with included graphics. The digital */
/* file #90 represents an image file to be included in #70 */
#70 = PRODUCT_DEFINITION('doc1_master', 'text file including graphics for doc1', #10, #80);
#80 = PRODUCT_DEFINITION_CONTEXT('digital document definition', #50, );
#90 = PRODUCT_DEFINITION('doc1_image', 'image to be included in doc1', #10, #80);
/* Entity #100 defines that the file #90 (image) is referenced by the */
/* file #70 (text master file) */
#100 = PRODUCT_DEFINITION_RELATIONSHIP('','reference',$,#70,#90);
/* other product data follows */
ENDSEC;
END-ISO-10303-21;
