IS:trackBegin
trackBegin
Scheme description / Schemenbeschreibung
Position of trackBegin in the XML-Tree / Position von trackBegin im XML-Baum
- Parent: <trackTopology>
- Children: (introduced with version 2.2) <geoCoord>, <bufferStop>, <connection>, <openEnd>, <macroscopicNode>
Multiplicity / Anzahl
Semantics / Bedeutung
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
- 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.
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- absPos: This is the position on a track as absolute mileage/chainage.
Das ist die Position des Elements im Referenzsystem der Strecken-Kilometrierung.
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- 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.
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Syntactic Constraints / Syntaktische Beschränkungen
- 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: tLengthM (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 raising [Sic!], falling
Semantic Constraints / Semantische Beschränkungen
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Best practice & Examples / Empfohlene Anwendung & Beispiele
Consider railML 2.3 example of Middle Rhine Railway by GPSinfradat.
TrackID | LineID | BeginElementType | EndElementType | OCP Start | OCP End |
---|---|---|---|---|---|
26301 | 2630 | oE | mN | KKO | FBGK |
35102 | 3510 | oE | mN | FMZ | FBGK |
35113 | 3511 | mN | oE | FBGK | SBKNG |
This code example defines track begin that is an open end.
<trackBegin id="tB26301" pos="0" absPos="91050"> <openEnd id="oEb26301"/> </trackBegin>
This code example defines track begin that is a macroscopic node.
<trackBegin id="tB35113" pos="0" absPos="-110"> <macroscopicNode ocpRef="ocpFBGK"/> </trackBegin>
Consider railML 2.2 example of East Saxony railway network by FBS.
This code example defines track begin that is a macroscopic node.
<trackBegin id='trn_DN_80.6212_1' pos='0' absPos='102100'> <macroscopicNode ocpRef='ocp_DN'/> </trackBegin>
Notes / Anmerkungen
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
Not yet described. / Noch nicht beschrieben.