rail:signalRef 

reference to a (main) signal that is valid for a train waiting at the stop post

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

Element Information

Model

Attributes

QName Type Fixed Default Use Inheritable Annotation
ref rail:tGenericRef required 
reference is required because it's the purpose of the element
Wildcard: ANY attribute from ANY namespace OTHER than 'http://www.railml.org/schemas/2016'

Source 

<xs:element name="signalRef" type="rail:tElementWithReference" minOccurs="0" maxOccurs="unbounded">
  <xs:annotation>
    <xs:documentation>reference to a (main) signal that is valid for a train waiting at the stop post</xs:documentation>
    <xs:documentation source="http://wiki.railml.org/index.php?title=IS:signalRef_stopPost"/>
  </xs:annotation>
</xs:element>

Sample