A term applied to an operation(say,parity checking) or to a hardware element(say,microcode storage) that is not evident to a user program and need not be considered by a programmer.

• 用于描述操作（如奇偶校验）或硬件元件（如微码存储器）的术语，对用户程序来说是隐蔽的，且不需要由程序员来考虑。