Since you asked --
Initial RR sales of the RB211 were the -22B rating. However, they could not produce engines that actually met that thrust rating, so they delivered a derated -22C model with attendant aircraft penalties (and financial penalties to RR & Lockheed, I'm sure).
But development refinement continued, until the machine met its original guarantees. Existing -22C's were upgraded at last to -22B, and finally the -22C was stricken from the type certificate. (Swept under the carpet, we might say)
But as late as 1986 I witnessed a dozen or more RR technicians at a medium-sized Middle East engine shop, scurrying to keep a fleet of RB's in dispatchable condition--average time on wing was a small fraction of the competitors. RR provided the labor force free of charge - which helped contain the airline's costs somewhat.