Single Core Specification
The figure above illustrates the specification of a single core wire. The WireSpecification is the PartOrUsageRelatedSpecification describing the PartVersion. In order to make it possible to reuse the specifications of wire elements in different wires or multi-cores (see Multi Core Specification), the actual properties and the structure of a wire is defined in a WireElementSpecification. The capabilities of a wire element are defined by the specifications referenced from the WireElementSpecification (e.g. a InsulationSpecification or a CoreSpecification)
The WireElement is the context specific handle of a WireElementSpecification in the context of a WireSpecification (primarily needed for multi cores, but due to a consistent modelling approach also mandatory for single cores). The WireElements is used as a handle for referencing, when a WireSpecification is instantiated (e.g. with a PartOccurrence).
If a wire element has multiple capabilities (e.g. insulation and core), then there are, in theory, multiple possible representations (see the figure below). It is recommended to always use the minimal representation of WireElementSpecification otherwise it inflates the number of objects without additional information.
Multi Core Illustration
This illustration shows an example of a multi core. The example uses a multi core, which is insulated with a grey insulation, shielded and which contains two FLRY cores of different colouring that are a twisted pair.
Multi Core Specification
The figure displays the representation of the multi core wire example in the VEC. The hierarchy of the wire is highlighted in the figure in green. The specification of the brown and green FLRY core (0.35-BRGN) is actually the same as the specification in the single core example (highlighted by the red outline in the figure). It is reused and not defined redundantly. Since it is the same WireElementSpecification object, the context specific naming of the WireElement is necessary, as mentioned in the single core example (highlighted in yellow).
The only difference between the two WireElements representing the two cores is the coloring of the insulation. Therefore the two WireElementSpecifications share the same CoreSpecification, but have individual InsulationSpecifications. In the context of the displayed WireSpecification the Brown & Green Core is addressed with the identification “1”, the second Core is addressed with the identification “2”. The two Cores are grouped together by a third WireElementSpecification (2x0.35-BRGN-RTBL).
This third WireElementSpecification defines the type of grouping by a WireGroupSpecification. In the example the Grouping is the definition of a twist of the two Cores. It also defines the insulation around the two SubWireElements by an InsulationSpecification. Since the defined wire has a conductive shield as well, the described WireElementSpecification references a ShieldSpecification, too. Again, this is the minimal possible representation of the wire element. The cross section area in the ShieldSpecification defines the nominal cross section area of the conductive material used in the shield.
Multi Core with multiple Usage of the same WireElementSpecification - Illustration
This illustration show an example of a more complex multi core. The example is a simplified CAT cable with only two twisted pairs, which are insulated with a grey insulation and shielded. In theory the white wires of both pairs are “red-striped” and “green-striped” to match the corresponding coloured wires. In reality they are often just pain white and therefore can be defined with the same wire specification.
Multi Core with multiple Usage of the same WireElementSpecification - Specification
To display the CAT cable and its SubWireElements, the hierarchy of the WireElementSpecifications (green) must be reflected in the hierarchy of the WireElements (yellow). The figure shows the CAT cable itself with its shield (“SHIELD”) and the contained cable pairs (“PAIR-1” and “PAIR-2”). Each cable pair consists of the wires themselves (e.g. “CORE-1a” and “CORE-1b” for “PAIR-1”). As each of the cable pairs has a white wire with the same WireElementSpecification, they share the this specification. However, there are individual WireElement in order the keep them distinctive and unambiguously referenceable (e.g. from a WireElementReference.