rail:trackBegin 

this node marks the begin of the track defined by its relative position pos=0

http://wiki.railml.org/index.php?title=IS:trackBegin

Element Information

Model

rail:geoCoord{0,1} , (rail:connection | rail:bufferStop | rail:openEnd | rail:macroscopicNode)
Children: rail:bufferStop, rail:connection, rail:geoCoord, rail:macroscopicNode, rail:openEnd

Attributes

QName Type Fixed Default Use Inheritable Annotation
absDir rail:tMileageDirection optional 
the starting direction of the mileage related to the track
absPos rail:tLengthM optional
absPosOffset rail:tLengthM optional 
DEPRECATED, not needed, not used
id rail:tGenericID required
pos rail:tLengthM required

Source 

<xs:element name="trackBegin" type="rail:eTrackBegin">
  <xs:annotation>
    <xs:documentation>this node marks the begin of the track defined by its relative position pos=0</xs:documentation>
    <xs:documentation source="http://wiki.railml.org/index.php?title=IS:trackBegin"/>
  </xs:annotation>
</xs:element>

Sample