Provided are an apparatus, a memory device, and a method for storing a plurality of parameter codes for an operation parameter. The memory device includes a mode register and a control logic circuit. To set a first operating condition and a second operating condition for one operation parameter, the mode register stores a first parameter code for the operation parameter and a second parameter code, which is expressed as an offset value from the first parameter code. The control logic circuit sets the first operating condition as a current operating condition of the memory device by using the first parameter code based on a first control code and sets the second operating condition as the current operating condition of the memory device by using the first parameter code and the second parameter code based on a second control code.