assigning_reference

Template:— assigning_reference_data (asg_rd)
Capability:assigning_reference_data

Date: 2009/06/10 09:22:49
Revision: 1.30

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

This section specifies the template assigning_reference_data.

NOTE The template has been defined in the context of the capability assigning_reference_data which provides an overall description of the relevant parts of the ISO 10303-239 information model and a description of related templates.

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

Description

This template describes the classification of something as being a member of a class, where the definition of that class is defined in a given external Reference Data Library (RDL).

This template illustrates the most simplified assignment of reference data, where:

The External_class_library.description attribute is not populated;
The External_class.name attribute uniquely identifies the class in the reference data library (i.e. External_class.id is not required);

NOTE There is also a template for assigning codes for classification to entity instances in a data set (assigning_code). The usage of the assigning_code template applies when the assigned code isn't defined as a class within a Reference Data Library.

NOTE For DEXlib edition 1, this template is also used for representing 'Same_as' associations between entity instances in a data set and individuals in a Reference Data Library. 'Same_as' means that an entity instance in a data set represents the same thing as the individual defined in the RDL. The use of this template for 'Same_as' associations will be superseded in DEXlib edition 2 by the use of the new 'Same_as_identification' entity and its associated template.

NOTE For DEXlib edition 1, the External_class.name attribute is populated with the name of the class being referenced in an RDL, and the External_class_library.id attribute identifies the RDL where this class is defined. This will be superseded in DEXlib edition 2, where the External_class.id attribute will be populated with the full HTTP URN identifying the source where the class is defined (RDL and class name), and the External_class_library.id attribute will identify the context onthology for an actual data exchange.

Model diagrams

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

Figure 1 — Attribute values set by the template 'assigning_reference_data'.

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

Figure 2 — Graphical representation of the template 'assigning_reference_data'.

Input parameters

The following input parameters are defined for this template:

class_name (Type='CLASS')

The name of the External_class being used.

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

classifications: "PLCS-ARM-LF-THING" (urn:plcs:rdl:std:PLCS-ARM-LF-THING)

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

The id of the External_class_library that stores the definition for the class being used.

items (Type= 'SELECT (classification_item)' )

The items to which the External_class is assigned.

Reference parameters

The following reference parameters are defined for this template:

ext_class(Type='ENTITY (External_class)')

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

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

%^target = $assigning_reference_data.ext_class%

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

ext_class_lib(Type='ENTITY (External_class_library)')

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

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

%^target = $assigning_reference_data.ext_class_lib%

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

class_asg(Type='ENTITY (Classification_assignment)')

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

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

%^target = $assigning_reference_data.class_asg%

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

Uniqueness constraints

The following parameter combinations specify a uniqueness constraint:

Unique constraint: Classification_assignment

Each instance of the entity (Classification_assignment) within the data set shall be uniquely identified by a combination of the following parameters on this template (assigning_reference_data) namely: ecl_id, class_name, items.
The instance is referenced by the following template parameter: class_asg.

Any given classification shall only be assigned to an item once.

Unique constraint: External class

Each instance of the entity (External_class) within the data set shall be uniquely identified by a combination of the following parameters on this template (assigning_reference_data) namely: class_name, ecl_id.
The instance is referenced by the following template parameter: ext_class.

Unique constraint: External class_library

Each instance of the entity (External_class_library) within the data set shall be uniquely identified by the following parameters on this template (assigning_reference_data) namely: ecl_id.
The instance is referenced by the following template parameter: ext_class_lib.

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 Templates Help/Information section.

Classification_assignment

-- Mark the Classification_assignment entity as referable when this template is used.
-- In other words, bind the Classification_assignment instance to the reference
-- parameter class_asg
%^class_asg = Classification_assignment%
Classification_assignment.role = '/IGNORE'
Classification_assignment.items -> @items
Classification_assignment.assigned_class -> External_class
External_class

-- Mark the External_class entity as referable when this template is used.
-- In other words, bind the External_class instance to the reference
-- parameter ext_class
%^ext_class = External_class%
External_class.id = '/NULL'
External_class.description = '/IGNORE'
External_class.name = @class_name

-- Mark the External_class_library entity as referable when this template is used.
-- In other words, bind the External_class_library instance to the reference
-- parameter ext_class_lib
%^ext_class_lib = External_class_library%
External_class.external_source -> External_class_library
External_class_library.id = @ecl_id
External_class_library.description = '/IGNORE'

The following entities are instantiated with attributes as specified:

Entity in path	Value	Inherited from
Classification_assignment.role	'/IGNORE'	—
External_class.id	'/NULL'	Class.id
External_class.description	'/IGNORE'	Class.description
External_class.name	@class_name	Class.name
External_class_library.id	@ecl_id	—
External_class_library.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:

/assigning_reference_data(items='#2', class_name='Part_identification_code', ecl_id='urn:plcs:rdl:std')/

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

Figure 3 — Instance diagram instantiated by the template example

The instance model in STEP ASCII exchange file format (ISO 10303 Part 21 syntax) is:


                  #1=PART('/IGNORE', '/IGNORE', '/IGNORE');
                  #2=IDENTIFICATION_ASSIGNMENT('TYRES-010101', '/IGNORE', '/IGNORE', (#1));
                  #3=EXTERNAL_CLASS_LIBRARY('urn:plcs:rdl:std', '$');
                  #4=EXTERNAL_CLASS('/NULL', 'Part_identification_code', '/IGNORE', #3);
                  #5=CLASSIFICATION_ASSIGNMENT(#4, (#2), '/IGNORE');

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:

/assigning_reference_data(items='#2', class_name='Part_identification_code', ecl_id='urn:plcs:rdl:std')/

Figure 4 — Invocation of template - graphical presentation

Characterizations

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