PDM-UG: Properties Associated with Product Data
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This page belongs to the PDM Usage Guide.
The PDM Schema allows specifying properties associated with product data. To specify properties associated with product data, a property definition tree is instantiated that links a representation of the property values to the described object that is the object with which the property is associated. The type of the property is given by the value of the attribute property_definition.name.
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The Instance Model: EXPRESS entities and attributes
The EXPRESS entities and attributes used to support the requirements of property definitions associated with product data are illustrated in Diagram 6.
Property definition
A property_definition is, in the given context, a property that characterizes a part. In the given context, it applies to a product_definition that represents a life cycle and application domain specific view on a part.
Attributes
| ENTITY property_definition | Attribute Population | Remarks |
| name | type: identifier = string | Provides the property type name |
| description | type: text = string | OPTIONAL |
| definition | type: entity = here: product_definition | References product_definition as the element of part identification that is described by the property. |
===Preprocessor Recommendations=== The name attribute characterizes the kind/type of the property. For the property_definition.name attribute, a number of predefined names for specific properties exist. Preprocessor should use these values where applicable.
===Postprocessor Recommendations=== None specified.
===Related Entities=== None specified.
Property definition representation
A property_definition_representation is, in the given context, an association between a property and its representation.
Attributes
| ENTITY property_definition_representation | Attribute Population | Remarks |
| definition | type: entity = property_definition | References associated property_definition |
| used_representation | type: entity = representation | References associated representation |
===Preprocessor Recommendations=== None specified.
===Postprocessor Recommendations=== None specified.
===Related Entities=== None specified.
Representation
A representation, in the context of part properties, is a collection of one or more measure_representation_items related to a property_definition via a property_definition_representation.
Attributes
| ENTITY representation | Attribute Population | Remarks |
| name | type: label = STRING | shall be instantiated with 'property value' |
| items | type: entity = measure_representation_item | the items that constitute the representation of the document property |
| context_of_items | type: entity = representation_context |
===Preprocessor Recommendations=== The name attribute shall be instantiated as 'property value' to indicate that the representation relates to a property value.
===Postprocessor Recommendations=== None specified.
===Related Entities=== None specified.
Representation context
The representation_context defines the context of interpretation for the values of items in a representation.
Attributes
- The context_identifier attribute identifies the context.
- The context_type attribute specifies the type of the context.
| ENTITY representation_context | Attribute Population | Remarks |
| context_identifier | type: label = string | |
| context_type | type: text = string |
===Preprocessor Recommendations=== None specified.
===Postprocessor Recommendations=== None specified.
===Related Entities=== None specified.
Measure representation item
A measure_representation_item is, in the property context, a value element that participates as an item in one or more representations to define the respective properties. The given numeric value is associated with the relevant unit.
Attributes
| ENTITY measure_representation_item | Attribute Population | Remarks |
| name | type: label = STRING | the name attribute indicates the name of the represented property |
| value_component | type: select = measure_value | |
| unit_component | type: entity = unit |
===Preprocessor Recommendations=== For the unit_component it is recommend to do complex instantiations of named_unit with si_unit or named_unit with conversion_based_unit.
===Postprocessor Recommendations=== None specified.
===Related Entities=== None specified.
The Instance Model: STEP exchange file format (ISO10303 Part 21 syntax)
/* Entities #5020 to #5070 assert that the #290 defined view */
/* of part has a mass of 3KG */
#5020 = PROPERTY_DEFINITION('mass property', $, #290);
#5030 = PROPERTY_DEFINITION_REPRESENTATION(#5020, #5040);
#5040 = REPRESENTATION('property value', (#5060), #5050);
#5050 = REPRESENTATION_CONTEXT(, );
#5060 = MEASURE_REPRESENTATION_ITEM('mass', MASS_MEASURE(3000), #5070);
#5070 =(NAMED_UNIT(*) MASS_UNIT() SI_UNIT($,.GRAM.));
