4 Information requirements

This clause specifies the information requirements for the Requirement view definition relationship application module. The information requirements are specified as the Application Reference Model (ARM) of this application module.

NOTE 1  A graphical representation of the information requirements is given in Annex C.

NOTE 2  The mapping specification is specified in 5.1. It shows how the information requirements are met by using common resources and constructs defined or imported in the MIM schema of this application module.

This clause defines the information requirements to which implementations shall conform using the EXPRESS language as defined in ISO 10303-11. The following begins the Requirement_view_definition_relationship_arm schema and identifies the necessary external references.

4.1 Required AM ARMs

The following EXPRESS interface statements specify the elements imported from the ARMs of other application modules.

EXPRESS specification:

*)
USE FROM Product_view_definition_relationship_arm;    --  ISO/TS 10303-1041



USE FROM Requirement_view_definition_arm;    --  ISO/TS 10303-1141
(*



NOTE 1   The schemas referenced above are specified in the following part of ISO 10303:

Product_view_definition_relationship_arm	ISO/TS 10303-1041
Requirement_view_definition_arm	ISO/TS 10303-1141

NOTE 2   See Annex C, Figures C.1and C.2 for a graphical representation of this schema.

4.2 ARM entity definitions

This subclause specifies the ARM entities for this module. Each ARM application entity is an atomic element that embodies a unique application concept and contains attributes specifying the data elements of the entity. The ARM entities and definitions are specified below.

4.2.1 Requirement_collection_relationship   

A Requirement_collection_relationship is a type of Requirement_view_definition_relationship that is used to relate a parent (collection) requirement to its member requirements. This provides a method for collecting together a set of requirements and treating them as a single requirement, whilst still being able to refer to individual requirements.

NOTE    The inherited "relating_view" and "related_view" attributes have been renamed for purposes of clarity.

EXPRESS specification:

*)
ENTITY Requirement_collection_relationship
  SUBTYPE OF (Requirement_view_definition_relationship);
  SELF\Requirement_view_definition_relationship.primary RENAMED collection : Requirement_view_definition;
  SELF\Requirement_view_definition_relationship.secondary RENAMED member : Requirement_view_definition;
END_ENTITY;
(*

Attribute definitions:

collection: the Requirement_view_definition that the Requirement_collection_relationship identifies as a collection.

NOTE    This atribute points to the view definition of the requirement which collects together the member requirements.

member: the Requirement_view_definition that the Requirement_collection_relationship identifies as a member.

NOTE    This attribute points to the view definition of a requirement which constitutes a part of the collection.

4.2.2 Requirement_precedence_relationship   

A Requirement_precedence_relationship is a type of Requirement_view_definition_relationship where the related Requirement_view_definition has higher priority than the relating Requirement_view_definition.

EXPRESS specification:

*)
ENTITY Requirement_precedence_relationship
  SUBTYPE OF (Requirement_view_definition_relationship);
END_ENTITY;
(*

4.2.3 Requirement_view_definition_relationship   

EXPRESS specification:

*)
ENTITY Requirement_view_definition_relationship
  SUPERTYPE OF (ONEOF (Requirement_collection_relationship,
                       Requirement_precedence_relationship,
                       Tracing_relationship))
  SUBTYPE OF (View_definition_relationship);
  SELF\View_definition_relationship.relating_view RENAMED primary : Requirement_view_definition;
  SELF\View_definition_relationship.related_view RENAMED secondary : Requirement_view_definition;
WHERE
  WR1: primary :<>: secondary;
END_ENTITY;
(*

Attribute definitions:

primary: specifies a role of a Requirement_view_definition for the Requirement_view_definition_relationship. The primary Requirement_view_definition is the independent item if the relationship is a dependency relationship.

secondary: specifies a role of a Requirement_view_definition for the Requirement_view_definition_relationship. The secondary Requirement_view_definition is the dependent item if the relationship is a dependency relationship.

Formal propositions:

WR1: The primary shall not be the secondary.

4.2.4 Tracing_relationship   

A Tracing_relationship is a type of Requirement_view_definition_relationship that shows tracing from (traces_from) one requirement to another (traces_to).

EXAMPLE    A requirement on the performance of a catalytic converter in a car may be traced from a more general emissions requirement.

A requirement may trace to many other requirements and vice versa - this is achieved by creating multiple instances of the tracing relationship entity.

NOTE 1   The inherited "relating_view" and "related_view" attributes have been renamed for purposes of clarity.

NOTE 2   Properties may be attached to tracing relationships. This is intended to deal with "user defined" attributes which are common on tracing relationships in requirements tools.

EXPRESS specification:

*)
ENTITY Tracing_relationship
  SUBTYPE OF (Requirement_view_definition_relationship);
  SELF\Requirement_view_definition_relationship.primary RENAMED traces_from : Requirement_view_definition;
  SELF\Requirement_view_definition_relationship.secondary RENAMED traces_to : Requirement_view_definition;
END_ENTITY;
(*

Attribute definitions:

traces_from: the Requirement_view_definition that the Tracing_relationship traces from.

NOTE 3   This attribute points to the view definition of the requirement which traces to another requirement.

traces_to: the Requirement_view_definition that the Tracing_relationship traces to.

NOTE 4   This attribute points to the view definition of the requirement which traces from another requirement.

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