| Re: [railML2] @dir [message #2256 is a reply to message #2194] |
Mon, 07 October 2019 21:51   |
christian.rahmig
Messages: 436
Registered: January 2016
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Senior Member |
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Dear all,
considering the relevance for semantic rules in modelling railML 2.x,
any feedback (pro, con, mod, ...) on the topic below is highly appreciated.
Thank you very much and best regards
Christian
Am 27.05.2019 um 11:57 schrieb Christian Rahmig:
> Dear active railML community,
>
> the new Common scheme coordinator Thomas (together with Janne from JBD)
> initiated a discussion about the meaning and usage of the attribute
> @dir. While the starting point of the discussion was at the element
> <levelCrossing> (cp. [1]) the attribute is available for almost all
> instances of <trackElements> and <ocsElements> and therefore deserves an
> own thread here in the forum.
>
> I want to propose three rules:
>
> 1) The @dir attribute represents an "application direction" describing a
> direction of travel, for which the element has to be considered. There
> are elements with a clear application direction (e.g. <signal>), where
> the @dir attribute shall be used, but there are also other elements
> without a specific application direction (e.g. <levelCrossing>), where
> the @dir attribute shall not be used.
>
> 2) In railML 2, even linear elements (e.g. tunnel or bridge) are located
> with a single coordinate (and an additional @length attribute). This
> coordinate shall always refer to the center of this element and the
> value of the @length attribute shall be equally distributed before and
> after this location. The @dir attribute shall not be used.
>
> 3) For very long linear elements (e.g. Gotthard Base Tunnel), it is
> useful to model the element's "portals" instead of its center point. In
> that case, elements need to be placed at the begin and the end of the
> element oriented towards the center point. The @dir attribute shall be
> used to describe the orientation of the "portal", e.g. to define what is
> in the tunnel and what is outside the tunnel.
>
> What do you think about this approach? Do you agree or do you prefer
> erasing the third point? Any comment is highly appreciated...
>
> [1] https://www.railml.org/forum/index.php?t=msg&th=655& goto=2179&#msg_2179
>
> 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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