svg:MarkerValueType 

'marker' property/attribute value (e.g., 'none', %URI;)

Simple Type Information

Used By

Attributes svg:PresentationAttributes-Markers/@marker-end, svg:PresentationAttributes-Markers/@marker-mid, svg:PresentationAttributes-Markers/@marker-start

Source 

<simpleType name="MarkerValueType">
  <annotation>
    <documentation>'marker' property/attribute value (e.g., 'none', %URI;)</documentation>
  </annotation>
  <restriction base="string"/>
  <!-- need to check this one, its a shorthand value -->
</simpleType>