PHY.3:4.1 - Specify the physical change and what must remain usable

Start with the proposed input and output. Include the range of inputs and the performance required on them. For a machine expected to handle an unknown input, ask whether one fixed arrangement must work throughout that range or whether the arrangement may be chosen after learning the input. For fluctuating processes, distinguish a guarantee on every run from an average or an allowed failure probability. MMP.8 supplies that formulation when the choice or information condition is difficult.

Follow the resources that can participate in the transformation: material, energy, prepared states, information about the input, external controls and connections to the surroundings. Describe their relevant initial and final conditions. A charged auxiliary, a memory that accumulates records and an initially correlated pair can be consumed resources even if the visible output is unchanged. Use the physical theory to decide which such differences matter to the proposed restriction.

For repeated operation, state what the device must remain able to do. Return to an identical state is needed only when the requested operation or the physical argument requires it. If the construction uses a reset, include its physical change and resource use. A device that still performs the next operation can have changed state; a device restored in one observed variable can have exhausted another needed resource. A.3.3.TR helps choose a sufficient state description where these cases are unresolved.

The result is a physical transformation with its allowed side effects and input conditions. Keep an unspecified preparation visible as an unresolved premise. It can be useful to derive a conditional bound before that premise is settled.