Any visual entity; any graphical item, part, or visual property of an image or part of an image, including the image itself. Examples include lines, areas, colors and textures. Pictorial elements may have arbitrarily complex shapes and may be implicit, e.g. lines of perspective or outlined white spaces. Rectangular regions of an image are pictorial elements, and the entire image is also. Thus, Image is a subclass of PictorialElement. PictorialElements may be included in one another, giving a simple mereology of visual forms, with the property visualPartOf. Non-visual properties such as date or manner of creation are not considered to be PictorialElements. A property or aspect of an image can be considered to be a PictorialElment when it can be apprehended by vision alone.