2.3.4.2 Formatting Elements
A formatting element data graphic is a sheet element data graphic with supplementary constraints that allow the visual formatting properties of the Canvas to be updated by formula expressions. Each CT_Sheet element associated with a formatting element data graphic MUST specify the FillBackground, FillBackgroundTrans, FillForeground, FillForegroundTrans, FillPattern, LineColor, LineColorTrans or LineWeight attributes or MUST have one or more child elements of type CT_Geometry.
A formatting element data graphic MUST contain child elements of type Path, Ellipse, Rectangle, Canvas, TextBlock or Canvas.RenderTransform.
If a formatting element data graphic has a child element of type Path, then it MUST NOT have a child element of type Rectangle, and it MUST NOT have a child element of type Ellipse that is not a Model Ellipse.
If a formatting element data graphic has a child element of type Rectangle, then it MUST NOT have a child element of type Path or Ellipse.