Either one of seven different forms of defining a color or the special value "none" to indicate no value. (Note: When an element of this type fails schema validation, the error message may indicate failure to satisfy the format for NoneValueType, which is the last type checked, regardless of the actual intended type of the element). Examples: blue; #F80; #EE97A2; rgb(255,0,30); rgb(21.5%, 90%, 3.1%); none.