Mark, do you understand what does following paragraph mean :
"Rerating refers only to the configured aircraft maximum thrust limit as defined by the FMC, Partial take-off thrust reductions below the Aircraft FMC maximum thrust rating are considered derate, and do not qualify for rerated life limit"
Can you provide the Maintenance Manual Reference?
Rerate refers to "rating again" or new computation.
Derate refers to "down-rating" or setting limit lower. A derated takeoff setting will provide safe takeoff speed reference, but a slightly lower fuel burn.