Encoding of Ferry Cables.

[JeffWootton]

Initiated in discussions regarding S-101 Portrayal Catalogue Github repository Issue #452.

The related comments are:

A cable area is not only used to encode an area within which there are numerous cables. It is also used to encode where "a regulatory authority designates an area for the protection of a cable, or cables." (DCEG clause 14.3.1). This is the reason why restriction is an allowable attribute for the feature CableArea. I therefore do not have a problem with value 7 being an allowable value for categoryOfCable on CableArea, as the cable may have a regulatory surrounding area within which restrictions, such as stopping, anchoring ...) apply.

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Following on from my last comment, I think we may have overthought the addition of value 7 for categoryOfCable given that the FerryRoute feature has attribute ferry value 2 (cable ferry). I think we have now created 2 ways of encoding the same real-world instance, which should be avoided.

In terms of encoding a ferry cable and an associated area within which restrictions apply, I suggest that this should be done by encoding a FerryRoute of geometric primitive line to represent the cable position; and a CableArea feature having categoryOfCable = 7 (ferry) to encode the area in which restrictions apply. From a modelling perspective, this would mean retaining value 7 for categoryofCable but removing it as an allowable value for the CableSubmarine feature. The guidance should then be amended accordingly.

I will open a new GitHub Issue in the Documentation and FC GitHub repository to begin the discussion on this for post-Edition 2.0.0.