What characteristic defines an Overo pattern in horse coloring?

The defining characteristic of an Overo pattern in horse coloring is that the white markings do not cross the horse's back. This trait distinguishes Overos from other patterns, such as Paints, where white can cross the back and create a more uniform appearance. The Overo pattern is characterized by irregular, jagged spots of color and white, typically resulting in a more varied and striking appearance compared to solid or more uniform patterns.

Options that suggest white crosses over the back contradict the very essence of the Overo pattern, which is known for not having this feature. Similarly, a description of a solid color throughout the body does not align with the Overo pattern, as it inherently involves various colors and markings. Lastly, stating that there are only spots of black and white fails to capture the diversity of colors that can be present in Overos, which can involve a range of colors beyond just black and white. Therefore, understanding that the Overo pattern specifically lacks white crossing over the back is essential for recognition and categorization of this horse coloring pattern.