Draws the marker at the specified point and angle (in radians) .
Markers are drawn such that their reference point (i.e., RefX and RefY) is positioned at the given vertex. In other words, a translation transformation is constructed by the user agent to achieve the effect of having point ( RefX and RefY) within the marker content's coordinate system (after any transformations due to the ViewBox and AspectRatio properties) align exactly with the given vertex.
The contents of the marker are relative to a new coordinate system. The Units property determines an initial scale factor for transforming the graphics in the marker into the user coordinate system for the referencing element. An additional set of transformations might occur if there is a ViewBox specified, in which case the coordinate system for the contents of the marker will be transformed due to the processing of ViewBox and AspectRatio properties. If there is no ViewBox specified, then the assumed default value for the the ViewBox property has the origin of the ViewBox coincident with the origin of the viewport and the width/ height of the viewBox the same as the width/height of the viewport.