Users are not required to understand the property syntax ; it is handled automatically through internal schema mapping 处理。用户无需理解属性语法；它将通过内部架构映射自动处理。
2.
Physical data independence : the capacity to change the internal schema without having to change the conceptual schema 逻辑资料独立：不必改变外部纲要或应用程式，即可改变概念纲要的能力。
