2.1.11 [SVG11] Section 11.6.2, The 'marker' element
The specification states:
Properties inherit into the 'marker' element from its ancestors; properties do not inherit from the element referencing the 'marker' element. 'marker' elements are never rendered directly; their only usage is as something that can be referenced using the 'marker', 'marker-start', 'marker-end' and 'marker-mid' properties. The 'display' property does not apply to the 'marker' element; thus, 'marker' elements are not directly rendered even if the 'display' property is set to a value other than none, and 'marker' elements are available for referencing even when the 'display' property on the 'marker' element or any of its ancestors is set to none. Event attributes and event listeners attached to the contents of a 'marker' element are not processed; only the rendering aspects of 'marker' elements are processed.
IE9 Mode, IE10 Mode, and IE11 Mode (All Versions)
Properties of a marker element inherit at the point of reference, not from the ancestors of the marker element.