Use enumerated attribute values when you want the attribute values to be one of a fixed set of legal values 當你希望屬性值是一組合法的固定值時,那么,你不妨使用“列舉屬性值”的方法。
While characters that were not present in unicode 2 . 0 can be used in xml 1 . 0 character data , they are not allowed in important parts of xml such as element and attribute names , or enumerated attribute values 盡管unicode 2 . 0之外的字符也可以在xml 1 . 0文檔中使用,但不能用于xml的重要成分,如元素名和屬性名以及枚舉屬性值中。