property_value_relationship

Template:— property_value_relationship (prp_rel)

Date: 2008/01/22 08:39:36
Revision: 1.19

Cover Contents Description Model diags.Input params.Ref. params.Instantiation path Instance diags.Characterizations Issues

This section specifies the template property_value_relationship.

NOTE An explanation of a template and the associated instantiation path is provided in the Template overview section.

Description

This template describes how to establish a relationship between property value representations.

Model diagrams

The EXPRESS-G diagram in Figure 1 shows the templates and EXPRESS entities that are required to represent the template "property_value_relationship". The text highlighted in blue shows the template parameters.

NOTE In any exchange file, a class name should only be represented by a single instance of External_class.

AP239 Issue (RBN-1)

The ISO-10303-239 1st edition does not allow the assignment of reference data to Representation_relationship.

This has been raised as issue, RBN-1, against ISO 10303-239. The EXPRESS schema has been modified in DEXlib (Long form: dexlib/data/schemas/ap239_arm_lf.exp, short form: dexlib/data/schemas/ap239_arm_sf.exp). These changes will be made to ISO 10303-239 as a Technical Corrigendum at some stage.

Figure 1 — An EXPRESS-G representation of the Information model for property_value_relationship

The graphic for the template to be used in other EXPRESS-G diagrams is shown in Figure 2 below.

Figure 2 — The graphical representation of property_value_relationship template

Input parameters

The following input parameters are defined for this template:

rel_type (Type='CLASS')

Type of relation between property value representations.

The following classes and their sub-classes can be used:

classifications: "Representation_relationship" (urn:plcs:rdl:std:Representation_relationship)

rel_type_ecl_id (Default=urn:plcs:rdl:std,Type='URN')

The identifier of the External_class_library storing the definition of the class referenced by the parameter @rel_type.

relating (Type= 'ENTITY (Representation)' )

The earlier, or preceding, representation value of the property, represented by a (subtype of) Representation.

related (Type= 'ENTITY (Representation)' )

The later, or succeeding, representation value of the property, represented by a (subtype of) Representation.

Reference parameters

The following reference parameters are defined for this template:

rep_rel(Type='ENTITY (Representation_relationship)')

Allow the Representation_relationship entity instantiated in this path to be referenced when this template is used.

Note: The Representation_relationship entity can be referenced in a template path by:

%^target = $property_value_relationship.rep_rel%

where target is the parameter to which the Representation_relationship is bound.

Instantiation path

The instantiation path shown below specifies the entities that are to be instantiated by the template.

A description of templates and the syntax for the instantiation path is provided in the Reading Capability Templates help section.

-- Instantiate a Representation_relationship
Representation_relationship

-- Set the Representation_relationship attributes to be ignored
Representation_relationship.relation_type = '/IGNORE'
Representation_relationship.description = '/IGNORE'
%^rep_rel = Representation_relationship%

-- Assign reference data for relation type
/assigning_reference_data(
    items=^rep_rel,
    class_name=@rel_type,
    ecl_id=@rel_type_ecl_id)/

-- Assign the relation to the preceding representation
-- e.g. Earlier value
Representation_relationship.rep_1 -> @relating

-- Assign the relation to the succeeding representation
-- e.g. Later value
Representation_relationship.rep_2 -> @related

The following entities are instantiated with attributes as specified:

Entity in path	Value	Inherited from
Representation_relationship.relation_type	'/IGNORE'	—
Representation_relationship.description	'/IGNORE'	—

Instance diagrams

The instance diagram in Figure 3 shows an example of the EXPRESS entities and templates that are instantiated by the template:

/property_value_relationship(rel_type='Succession_relationship', rel_type_ecl_id='urn:plcs:rdl:std', relating='#8', related='#26')/

(an illustration of the consolidated property_value_relationship template is shown in Figure 4 below.)

Figure 3 — Entities instantiated by property_value_relationship template

The instance diagram in Figure 4 shows the graphic symbol for the template that is to be used in other instance diagrams. The example template is:

/property_value_relationship(rel_type='Succession_relationship', rel_type_ecl_id='urn:plcs:rdl:std', relating='#8', related='#26')/

Note that the assigning_reference_data template is used in the diagram. Namely:

/assigning_reference_data(items='#46', class_name='Succession_relationship', ecl_id='urn:plcs:rdl:std')/

Figure 4 — Instantiation of property_value_relationship template

Characterizations

No common characterizations of the template property_value_relationship have been identified. However, the ISO 10303-239 EXPRESS model may enable other assignments to the entities instantiated by the template.