| Re: [railML 2] <speedChange> semantic constraints revision [message #3084 is a reply to message #3080] |
Wed, 10 May 2023 13:24   |
Thomas Nygreen
Messages: 68
Registered: March 2008
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Dear all,
I note that the current semantic constraint ("every <track>") is far more extensive than the origin referred to in the background information (ticket #425 [1] pointing to railML2.4nor, which requires <speedChange>s to be placed on "a <trackBegin> or <trackEnd> that is not connected to another track"). Was this difference intended? While our Wiki documentation says that "A <speedChange> defines a track element in which position the maximum allowed speed on a track changes", this semantic constraint would mean that a large share of <speedChange>s are not placed in a position where the maximum speed changes, but on all points where <track>s are split. It seems to me that with this use the element should not have a name containing "Change". While we cannot change the name, we should modify either the documentation or the semantic constraint.
As Christian, I agree with Larissa's points (1) and (2). The question in (3) is more tricky. How would you use a file that contains speeds for some tracks but not all? I would assume that an exporting or importing software either uses speed information on all tracks or on none of them. Also, how would the consuming software know which is which? (Should the initial <speedChange> work as a flag that this <track> has speed information?)
[1] https://development.railml.org/railml/version2/-/issues/425
Best regards,
Thomas
Thomas Nygreen – Common Schema Coordinator
railML.org (Registry of Associations: VR 5750)
Altplauen 19h; 01187 Dresden; Germany www.railML.org
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