|Visio XML Reference|
Specifies the color used for the background of the shape's fill pattern.
Optional string. Represents a unit of measure. The default is COLOR. For details about COLOR, see Units of measure.
Optional string. Represents the element's formula. This attribute can contain one of the following strings: "someFormula" if the formula exists locally, "No Formula" if the formula is locally deleted or blocked, or "Inh" if the formula is inherited.
If the attribute is not present, the element's formula is a simple constant, for example, <element>5</element>.
Optional string. Indicates that the formula evaluates to an error. The value of Err is the current value (an error message string); the value of the element is the last valid value.
To set the color, enter a number from 0 to 23 or the RGB value in hexadecimal notation. The numbers 0 to 23 correspond to a color in the document color table, which is contained in the Colors element.
You can also specify a custom color by using its RGB value, or by specifying a formula. Enter a custom color in the following format: #rrggbb, where rr, gg, and bb are hexidecimal notation.
If a formula can be reconstructed from the RGB value, the formula is not saved. For example, because the formula RGB(255, 153, 0) represented in hexadecimal notation is #ff9900, the value #ff9900 would be saved in the DatadiagramML file.
FillBkgnd cell (Fill Format section)