I'm looking at the documentation for INPUT-FILES and OUTPUT-FILES and I see this:

  (defgeneric output-files (operation component)
    (:documentation "Methods for this function return two values: a list of output files
corresponding to this action, and a boolean indicating if they have already been subjected
to relevant output translations and should not be further translated.

Methods on PERFORM *must* call this function to determine where their outputs are to be located.
They may rely on the order of the files to discriminate between outputs.
"))
  (defgeneric input-files (operation component)
    (:documentation "A list of input files corresponding to this action.

Methods on PERFORM *must* call this function to determine where their inputs are located.
They may rely on the order of the files to discriminate between inputs.
"))

Missing in the above is an explanation of how to tell INPUT-FILES whether to apply output translations or not.

Is this left to the author of the relevant PERFORM method? Or is there something one should do when writing a PERFORM method or an operator definition?