5 Material property representation schema

5.1 General

The subjects of the material_property_representation_schema are the representations of engineering properties and of the conditions under which these property representations are valid.

Short names of entities defined in this schema are described in Annex A. Unambiguous identification of this schema is defined in Annex B.

REFERENCE FROM product_property_representation_schema    --  ISO 10303-41
  (property_definition_representation);



REFERENCE FROM shape_dimension_schema    --  ISO 10303-47
  (dimensional_characteristic_representation);



REFERENCE FROM process_property_representation_schema    --  ISO 10303-49
  (action_property_representation,
   resource_property_representation);



REFERENCE FROM support_resource_schema    --  ISO 10303-41
  (label,
   text);
(*



NOTE 1   The schemas referenced above are specified in the following parts:

product_property_representation_schema	ISO 10303-41
shape_dimension_schema	ISO 10303-47
process_property_representation_schema	ISO 10303-49
support_resource_schema	ISO 10303-41

NOTE 2   See Annex D for a graphical representation of this schema.

5.2 Fundamental concepts and assumptions

The following are the fundamental concepts and assumptions related to the representation of engineering properties:

• multiple representations of a property are possible including the use of numeric values, parametric or fundamental equations, graphical representations and non-numeric values;

  NOTE    The distinction between a concept and the representation of a concept is described in ISO 10303-43

• the value of a property may be assigned or measured;
• if the value is measured, the resulting value will depend on the method of measurement and on the conditions used in applying the method;
• if the value is assigned, the conditions under which that assignment is valid may be specified;
• in the case of either assignment or measurement, the conditions under which the value is valid are expressed as a set of quantitative and qualitative data which form the data environment.

EXAMPLE    The ambient conditions for a measurement may be expressed as 'room air' (a qualitative condition) or air at the quantitative conditions specified as 20 degrees Celsius and 1 atmosphere pressure.

The conditions of the measurement method may be maintained as constant throughout the measurement. Alternatively, some conditions may be varied independently of other conditions to provide a set of related properties.

Not all values of properties need to be expressed quantitatively, i.e. by numerical values. Values may also be expressed qualitatively, i.e. by a description.

EXAMPLE    Colour, through expressible quantitatively, is mostly described qualitatively by words such as 'red', 'Aegean blue', 'metallic grey', etc.

5.3 material_property_representation_schema type definition

5.3.1 characterized_property_representation   

EXPRESS specification:

*)
TYPE characterized_property_representation = SELECT
   (action_property_representation,
    dimensional_characteristic_representation,
    property_definition_representation,
    resource_property_representation);
END_TYPE;
(*

5.4 material_property_representation_schema entity definitions

5.4.1 data_environment   

EXPRESS specification:

*)
ENTITY data_environment;
  name : label;
  description : text;
  elements : SET[1:?] OF characterized_property_representation;
END_ENTITY;
(*

Attribute definitions:

name: the word or group of words by which the data environment is referred to.

description: a narrative description of the data environment.

elements: the set of conditions under which a data environment is valid.

5.4.2 data_environment_relationship   

A data_environment_relationship is an association between two data_environments.

NOTE    An association may exist between data_environments that relate to different material_property entities or between different representations of the same material_property.

EXPRESS specification:

*)
ENTITY data_environment_relationship;
  name : label;
  description : text;
  relating_data_environment : data_environment;
  related_data_environment : data_environment;
END_ENTITY;
(*

Attribute definitions:

name: the word or group of words by which the data_environment_relationship is referred to.

description: a narrative description of the data_environment_relationship.

relating_data_environment: the data_environment that acts as the parent of the related_data_environment.

related_data_environment: the data_environment that acts as the child of the relating_data_environment.

NOTE    The roles of the relating_data_environment and the related_data_environment attributes are defined in the part of ISO 10303 that uses or specialises this entity.

5.4.3 material_dimensional_characteristic_representation   

A material_dimensional_characteristic_representation is a type of dimensional_characteristic_representation. A material_dimensional_characteristic_representation specialises a dimensional_characteristic_representation to associate it with a data_environment.

EXPRESS specification:

*)
ENTITY material_dimensional_characteristic_representation
  SUBTYPE OF (dimensional_characteristic_representation);
  dependent_environment : data_environment;
END_ENTITY;
(*

Attribute definitions:

dependent_environment: the conditions under which a representation of a dimension is valid.

5.4.4 material_property_representation   

A material_property_representation is a type of property_definition_representation. A material_property_representation specialises a property_definition_representation to associate it with a data_environment.

NOTE    The association with a product is through reference to a material_property entity which has a characterized_definition.

EXPRESS specification:

*)
ENTITY material_property_representation
  SUBTYPE OF (property_definition_representation);
  dependent_environment : data_environment;
END_ENTITY;
(*

Attribute definitions:

dependent_environment: the conditions under which a property representation is valid.

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