From railML 2 Wiki
Jump to navigation Jump to search


Scheme description / Schemenbeschreibung / Description du schéma

Position of trackBegin in the XML-Tree / Position von trackBegin im XML-Baum / position de trackBegin dans l’aborescence XML

Multiplicity / Anzahl / Multiplicité


Semantics / Bedeutung / Sémantique

The trackBegin defines the start of a track in the railML file. It could be seen as a "vertex" in a "graph" where the track is an "edge".
Please, be aware of the semantic constraint(s)!

Attributes of trackBegin / Attribute von trackBegin / Attributs de trackBegin

  • id: XML-file-wide unique, machine-interpretable identity, required for later referencing that element internally. For a detailed explanation see Dev:identities.
    XML-Datei-weit eindeutige, maschineninterpretierbare Identität, die für die spätere interne Referenzierung dieses Elements erforderlich ist. Für eine detaillierte Erklärung siehe Dev:identities.
  • pos: This is the position on a track defined as distance from its start (trackBegin) regardless the "absolute mileage" in @absPos.
    Das ist die Position des Elements auf einem Track i.S. der realen Entfernung zum trackBegin. Sie ist damit unabhängig von der mit absPos modellierten Strecken-Kilometrierung.
Note.png For an explanation of the differences between @pos and @absPos see <mileageChange>
  • absPos: This is the position on a track as absolute mileage/chainage.
    Das ist die Position des Elements im Referenzsystem der Strecken-Kilometrierung.
Note.png For an explanation of the differences between @pos and @absPos see <mileageChange>
  • absPosOffset (deprecated with version 2.1): The semantics of this attribute aren't very clear. It seems to be redundant to the definitions with mileageChanges in "overlapping regions".
  • absDir (introduced with version 2.2): Defines whether the mileage increases ("raising") or decreases ("falling") along the <track> from this trackBegin.
Note.png The value "raising" is a misspelling of "rising".
For downward compatibility reasons, this cannot be changed.

Syntactic Constraints / Syntaktische Beschränkungen / Contraintes syntactiques

  • id: xs:ID, required
    a string, starting with a letter (a..zA..Z) or an underscore (_),
    followed by a non-colonized and non-spaced string consisting of letters, digits, points (.), dashes (-) or underscores (_)
  • pos: tLengthM (xs:decimal, 6 fraction digits, length value measured in meter); required; must be greater than or equal to zero, less than or equal to the track's length
    The start of the track is described by a pos value of zero.
  • absPos: xs:decimal, 6 fraction digits, length value measured in meter; optional
    If two <track>s are connected, the absPos values of the connected <trackBegin> and <trackEnd> must be identical if both are provided and no mileageChange is defined at this point and both tracks belong to the same "mileage system" (typically the same line and same owner).
    If absPos is used in <trackBegin> then it should be used in <trackEnd> for unambiguity reasons, too.
  • absPosOffset: xs:decimal, 6 fraction digits, length value measured in meter; optional
  • absDir: xs:string, generic type for mileage direction statements; enumeration rising, falling

Semantic Constraints / Semantische Beschränkungen / Contraintes semantiques

Private-cloud-icon.png Proposed Semantic Constraint "IS:003":

Best practice & Examples / Empfohlene Anwendung & Beispiele / Bonnes pratiques & exemples

Missinginformation.png In this article there is information missing with respect to best practice around mileage changes. Please help improving the railML® wiki by filling the gaps. Possibly, you will find further details on the discussion pageFerri Leberl (talk) 16:52, 3 January 2018 (CET)

Notes / Anmerkungen / Notes

General information on positioning

Positive pos values describe the distance from the track's begin. The track length is derived from the pos value in <trackEnd>.

The absolute mileage refered to by absPos is usually found on technical drawings of the track layout or on mileage posts next to the track.

Open issues / Offene Punkte/Pendenzen / Questions ouvertes

Not yet described. / Noch nicht beschrieben. / Pas encore décrit.