1. A method of configuring and using a device, wherein the device has configuration memory space allocated to it for a plurality of functions, wherein at least one of the plurality of functions is implemented by the device, and wherein at least one of the plurality of functions is not implemented by the device, the method comprising the acts of: storing data in a header portion of the configuration space allocated to the function that is not implemented by the device, wherein the data indicates that the function is not implemented; programming a register that is in the remaining portion of the configuration space allocated to the function that is not implemented by the device; and accessing the programmed register.