●数据类型的数值属性并不限定数值的数据类型,适用于任何一种标量类型 例:枚举类型定义: type weekis(sunday, monday, tuesday, wednsday, thursay, friday, saturday); subtype sub_weekl is week range wednsday to friday subtype sub_week 2 is week range friday downto wednsday; 可得如下关系式: week left sunday weeknight=saturday week high =saturday weck’low= sunday sub_week1" leftwednsday Lb week 1’ight= friday sub_week1 high=friday sub_week1" low=wednsday sub week2 left=fric sub_week2 right=wednsday sub_week2 high=friday sub week2 low=wednsday⚫数据类型的数值属性并不限定数值的数据类型，适用于任何一种标量类型 例：枚举类型定义： type week is (sunday, monday, tuesday, wednsday, thursay, friday, saturday); subtype sub_week1 is week range wednsday to friday; subtype sub_week2 is week range friday downto wednsday; 可得如下关系式： week’left = sunday week’right=saturday week’high= saturday week’low = sunday sub_week1’left=wednsday sub_week1’right=friday sub_week1’high=friday sub_week1’low=wednsday sub_week2’left=friday sub_week2’right=wednsday sub_week2’high=friday sub_week2’low=wednsday