| [railML 2] Semantic Constraint at trackBegin and trackEnd [message #3054] |
Mon, 13 March 2023 14:42  |
Milan Wölke
Messages: 181
Registered: April 2007
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Senior Member |
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Hi all,
the Infrastructure Coordinator asked me to review the semantic constraints at <trackBegin> and <trackEnd> together with the Timetable developer group. When we did that we found that some constraints did not make sense to us so we reformulated them. In particular the constraint that the attribute @pos specified for a <trackBegin> was always supposed to be 0 didnt match the expectation of the developer group. The question raised was, that if there is an attribute that is supposed to always have the same value, why have an attribute at all.
Accordingly we changed the constraint to declare that a @pos value at <trackBegin> is always to be lower than the @pos value given at <trackEnd>. This raised another question, if the @pos of <trackBegin> should always be lower than @pos at <trackEnd> or if it may also have the same value. Having the same value would then mean that the described track has a length of 0. In this matter we wanted to ask the community.
Are you using zero length tracks in your models?
Can you deal with railML documents that include tracks like that during import?
Of course any comments on the current version of the semantic constrains liked below is very welcome.
https://wiki2.railml.org/wiki/IS:trackBegin#IS:003
https://wiki2.railml.org/wiki/IS:trackEnd#IS:002
Thanks in advance!
Best regards, Milan
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Hallo zusammen,
der Infrastrukturkoordinator bat mich, die Semantic Constraints bei <trackBegin> und <trackEnd> gemeinsam mit der Timetable Developer Group zu überprüfen. Dabei haben wir festgestellt, dass einige Einschränkungen für uns keinen Sinn ergeben, so dass wir sie neu formuliert haben. Insbesondere die Einschränkung, dass das für <trackBegin> angegebene Attribut @pos immer 0 sein sollte, entsprach nicht den Erwartungen der Entwicklergruppe. Es wurde die Frage aufgeworfen, warum es überhaupt ein Attribut gibt, wenn es immer denselben Wert haben soll.
Dementsprechend änderten wir die Einschränkung dahingehend, dass ein @pos-Wert bei <trackBegin> immer niedriger sein muss als der @pos-Wert bei <trackEnd>. Dies warf eine weitere Frage auf, nämlich ob der @pos-Wert von <trackBegin> immer niedriger sein sollte als der @pos-Wert von <trackEnd> oder ob er auch denselben Wert haben kann. Der identische Wert würde dann zur Folge haben, dass der beschriebene Track eine Länge von 0 hat. In diesem Zusammenhang wollten wir die Community fragen.
Verwenden Sie Gleise mit einer Länge von Null in Ihren Modellen?
Können Sie beim Import mit railML-Dokumenten umgehen, die solche Gleise enthalten?
Natürlich ist jeder Kommentar zur aktuellen Fassung der unten aufgeführten Semantic Constrains sehr willkommen.
https://wiki2.railml.org/wiki/IS:trackBegin#IS:003
https://wiki2.railml.org/wiki/IS:trackEnd#IS:002
Vielen Dank im Voraus!
Mit freundlichen Grüßen, 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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| Re: [railML 2] Semantic Constraint at trackBegin and trackEnd [message #3058 is a reply to message #3056] |
Tue, 14 March 2023 20:18  |
christian.rahmig
Messages: 505
Registered: January 2016
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Senior Member |
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Dear all,
apart from the feedback on the existence of zero length tracks (thank you David for your reply), I am very interested to hear/read who is using railML 2.x with tracks that do not start with @pos=0? Any feedback is highly appreciated to get a wholistic view on this issue.
Thank you very much and best regards
Christian
Christian Rahmig – Infrastructure scheme coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
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| Re: [railML 2] Semantic Constraint at trackBegin and trackEnd [message #3547 is a reply to message #3545] |
Tue, 08 April 2025 10:46 |
Christian Rößiger
Messages: 79
Registered: March 2015
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Member |
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Dear all,
sorry for my late answer. In certain cases we export tracks whose trackBegin element has an "pos"-value other than "0". I am not sure whether there is a specific usecase for this, finally we export the data in the same way the user entered it in our program. However all "pos" values of track elements should always be increasing, i.e. the position of trackEnd is always higher then the one of trackBegin.
But I'm a bit confused: When I look at the SemCons IS:002 and IS:003 under https://wiki2.railml.org/wiki/Dev:SemanticConstraints I don't see any hint, that the track must begin with "pos=0". Both SemCons seem to be still under discussion. So, is it the idea, to reject these two SemCon proposals and replace them with the restriction that the trackBegin-Position must always be zero?
Best regards
Christian
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