Home » railML newsgroups » railML.infrastructure » [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation (Ensuring that each netElement and netRelation belongs to exactly one RTM:level)
[railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3485] Thu, 27 February 2025 16:14 Go to next message
Larissa Zhuchyi is currently offline  Larissa Zhuchyi
Messages: 102
Registered: November 2022
Senior Member
Dear all

During the certification of a railML3 export interface we noticed that the railML3 schemas syntactically allow to define netElement and netRelation elements which belong to no level. Furthermore while testing a new version of railVIVID it became apparent that it's possible to have a syntactically valid railML file with intersecting network levels.

To prevent these issues, we suggest the following semantic constraint IS:022 and IS:023:

Each IS:netElement must belong to exactly one RTM:level.

Each IS:netRelation must belong to exactly one RTM:level.

Please let us know if you do not agree with the suggested semantic constraint IS:022 and IS:023 till 2025-04-30. How could the wording be improved to avoid misunderstandings especially for people new to railML?

Sincerely,

Larissa Zhuchyi – Ontology Researcher
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org

[Updated on: Tue, 04 March 2025 15:32]

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Re: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3487 is a reply to message #3485] Mon, 03 March 2025 09:05 Go to previous messageGo to next message
Rémi Collet is currently offline  Rémi Collet
Messages: 13
Registered: November 2024
Junior Member
I don't think that RTM restricts NetRelations from linking NetElements from different levels. Perhaps I am too used to RSM and there is a difference here, though ?

With that premice in mind, a NetRelation that links NetElements from different levels (say micro and macro) should be categorized as which ? I don't have a definitive answer, and to me, the NetRelation could be categorized as belonging to both levels in that case.

Ontologist @Infrabel (Belgian Railway Infrastructure Manager)
remicollet(at)infrabelbe

[Updated on: Mon, 03 March 2025 09:05]

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Re: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3491 is a reply to message #3487] Mon, 03 March 2025 13:38 Go to previous messageGo to next message
christian.rahmig is currently offline  christian.rahmig
Messages: 546
Registered: January 2016
Senior Member
Dear Rémi,

thank you for your feedback. The semantic constraints formulated by Larissa are focusing on linking each netElement and each netRelation with a level of aggregation. As a result, there should be no netElement and no netRelation that is not linked with any level. However, your question is valid and I want to re-formulate it to: "Can a netElement or netRelation be linked with more than one level of aggregation?"

Dear community, what do you think? As usual, any kind of feedback is highly appreciated...

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: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3496 is a reply to message #3491] Tue, 04 March 2025 11:31 Go to previous messageGo to next message
David Lichti is currently offline  David Lichti
Messages: 54
Registered: December 2020
Member
It seems to me that the association of a net relation to a topology level is implicitly given by the topology level of the related net elements. If both net elements are nodes in the graph representation in a particular level, then a net relation between them is an edge in the same graph. The explicit association of net relation to a topology level would then be redundant.

I agree that each net element (and, by consequence, each net relation) should belong to exactly one topology level. The semantic constraints IS:022 and IS:023 as proposed by Larissa look good to me.

I am not sure what it would mean for a net relation to connect two net elements from different topology levels. It is neither an edge in one graph, nor in the other. It feels like there should be another semantic constraint to exclude diagonal net relations. Relations between net elements should be either horizontal (using net relations [1]), or vertical (using the ordered [2] or unordered element collections [3]), but not diagonal.


[1] https://wiki3.railml.org/wiki/IS:netRelation
[2] https://wiki3.railml.org/wiki/RTM:elementCollectionOrdered
[3] https://wiki3.railml.org/wiki/RTM:elementCollectionUnordered

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Re: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3564 is a reply to message #3496] Mon, 14 April 2025 13:38 Go to previous messageGo to next message
christian.rahmig is currently offline  christian.rahmig
Messages: 546
Registered: January 2016
Senior Member
Dear David,

thank you very much for your feedback and semantic constraint proposal.
@all in the railML community: what is your opinion on that?

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: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3576 is a reply to message #3564] Tue, 22 April 2025 13:03 Go to previous messageGo to next message
Fredrik Jönsson is currently offline  Fredrik Jönsson
Messages: 12
Registered: June 2024
Location: Sweden
Junior Member
We don´t see any problem with the proposed semantic constraint for IS:022 and IS:023.

Fredrik Jönsson
Trafikverket - Swedish Transport Administration

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Re: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3578 is a reply to message #3576] Tue, 22 April 2025 14:57 Go to previous messageGo to next message
Stéphane Kaloustian is currently offline  Stéphane Kaloustian
Messages: 8
Registered: September 2024
Junior Member
Hi all

We don't see problems with the proposed constraints IS:022 and IS:023. In case the "same" netElement belongs to 2 levels, we would duplicate it, once in each level.

Regards
Stéphane Kaloustian
SBB Swiss Railways

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Re: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3590 is a reply to message #3578] Wed, 23 April 2025 22:25 Go to previous messageGo to next message
Mathias Vanden Auweele is currently offline  Mathias Vanden Auweele
Messages: 116
Registered: February 2025
Location: Brussels
Senior Member
Quote:
"Can a netElement or netRelation be linked with more than one level of aggregation?"
Yes, this is the case for the topology management system at Infrabel. NetElements can be shared between the micro and 'a' meso level. The meso level aggregates some more complex railway installations to make a more easy to read map. The associated positioning systems of the netelements are also more schematic for the meso level. But the NetElements are the same.

Mathias Vanden Auweele
Railway data freelancer
https://matdata.eu
Brussels, Belgium

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Re: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3995 is a reply to message #3590] Wed, 06 May 2026 17:52 Go to previous messageGo to next message
Milan Wölke is currently offline  Milan Wölke
Messages: 223
Registered: April 2007
Senior Member
Hi all,

in general I would agree with Larissas Semantic Contraint proposals. They reflect the way I would understand the model. Like David pointed out, connections between netElements of different levels would somehow connect the graphs when this should rather be done using aggregation.

@Mathias: Can you provide some short example how that would look like? I think I am missing something with your scenario. If the netElement is shared between meso and micro, how can you aggregate?

Best regards, Milan

Milan Hoffmann – Timetable schema coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org

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Re: [railML3] New semantic constraint restricting RTM:level, IS:netElement and IS:netRelation [message #3997 is a reply to message #3995] Thu, 07 May 2026 20:20 Go to previous message
Mathias Vanden Auweele is currently offline  Mathias Vanden Auweele
Messages: 116
Registered: February 2025
Location: Brussels
Senior Member
Hi Milan,

Quote:
If the netElement is shared between meso and micro, how can you aggregate?
When there's no need to aggregate between a micro and a meso level. :)

For example when a meso level is defined to only aggregate the tracks of an operational point of any type that is not a station (which is more or less the case for Infrabel). (I think I have seen a similar thing at SBB but I'm not 100% sure). So a meso level is aggregating the netelements of the yards, sidings, ... but does not make any changes to the station netelements or the open track netelements.

Then there's also the case of one network having multiple meso (or micro or macro) levels. In that case most netelements could be shared by multiple levels.

Mathias Vanden Auweele
Railway data freelancer
https://matdata.eu
Brussels, Belgium

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