ImageSource Class on MSDN Mistake?

I am unclear of what this means from the definition on ImageSource class on MSDN:

Represents a object type that has a width, height, and ImageMetadata such as a BitmapSource and a Dra开发者_如何学GowingImage.

This is an abstract class, DrawingImage and BitmapSource both derive from ImageSource, they are not part of the metadata.

I think it's a matter of associativity:

Represents a object type --- that has a width, height, and ImageMetadata --- such as a BitmapSource and a DrawingImage

i.e. the such as does not belong to the ImageMetadata.