| [railML3] Proposal for a new semantic constraint for associatedPositioningSystem [message #3537] |
Wed, 02 April 2025 13:18  |
Milan Wölke
Messages: 181
Registered: April 2007
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Senior Member |
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Hi all,
I'm writing to you on behalf of Christian today to propose a new semantic constraint for associatedPositioningSystem.
Background:
Typically, mileage systems are specified in railML 3 using a linearPositioningSystem which is specified in the common sub schema. The definition there allows to also describe discontinuities such as stretching of mileage (a kilometer in the mileagesystem (chainage) is stretched out over more than a kilometer in reality) or compression of mileage (a kilometer in reality is less than a kilometer in the mileage system). This is not taking into account mileage jumps such as gaps and overlaps. In order to describe this, the linearPositioningSystem allows usage of anchors. This is how it is meant to be described.
However, we realized that is is also possible to implicitly describe such situations on the level of the associatedPositioningSystem. Typically, for a linear netElement two intrinsic coordinates will be defined, one with @intrinsicCoord=0 and one with @intrinsicCoord=1. Often for each a linearCoordinate will be specified. The problem we realized now is, that if intrinsic coordinates with @intrinsicCoord between 0 and 1 were specified along with linearCoordinates then it is possible to implicitly describe a similar stretching and compression.
The proposed semantic constraint is aimed to make sure that this secondary way of describing is not used. We would propose the following constraint:
When specifying an intrinsic coordinate with 0 < @intrinsicCoord < 1, it needs to be ensured that a given linearCoordinate is aligned with the referenced linearPositioningSystem.
What are your thoughts on this. Do you think this wording captures what we intend to describe? Do you have concerns introducing such semantic constraint?`
Please let us know your feedback until end of April 2025, especially if you have concerns introducing this.
Thanks in advance.
Best regards, Milan
Milan Wölke – Timetable scheme coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
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