SVGTransform is the interface for one of the component transformations within an
SVGTransformList; thus, an SVGTransform object corresponds to a single
component (e.g., scale(…) or matrix(…)) within a transform attribute.
The unit type is not one of predefined unit types.
The unit type is not one of predefined unit types. It is invalid to attempt to define a
new value of this type or to attempt to switch an existing value to this type.