The cy property defines the y-coordinate for the center of the largest (that is, outermost) circle of a radial gradient. The gradient is drawn such that the 100% gradient stop is mapped to the perimeter of this largest (that is, outermost) circle. If you do not specify the cy property, the effect is the same as if you specify a value of 50%.
The cy value can be a percentage. When gradientUnits is userSpaceOnUse, percentages represent values that are relative to the current viewport. When gradientUnits is objectBoundingBox, percentages represent values that are relative to the bounding box for the object.
Properties inherit into the radialGradient element from its ancestors. Properties do not inherit from the element that references the radialGradient element.
radialGradient elements are never rendered directly. They exist so that you can reference them by using the fill and stroke properties.
The display property does not apply to the radialGradient element so radialGradient elements are not directly rendered even if the display property is set to a value other than none. radialGradient elements are available for referencing even when the display property on the radialGradient element or any of its ancestors is set to none.
- Scalable Vector Graphics: Gradients and Patterns, Section 13.4.3
Microsoft Developer Network: [Windows Internet Explorer API reference Article]