In my state the test is written with the assumption that FLC is the Code book number and FLA is the name plate number but others interpret it as all name plate data. It’s one of those ambiguous/controversial areas. The table covers only NEMA rated motors.
The accepted practice among some is to use the table for sizing short circuit protection and the name plate for overload protection. The reason for this is so you can swap motors without changing breakers/fuses and only need to adjust the overload. But technically the table is for when you don’t have name plate FLA, only horsepower. And what’s more if you are for instance going for type II protection you need to use the fuse types and sizes specified in NEMA ICS 2, which is a tighter requirement than NEC.
But there are plenty of motors outside that table. For instance compressors often have motors with crazy service factors like 1.25 or higher. Arbor saw motors and servo motors don’t follow anything resembling NEMA. Neither do wound rotor motors. What about 4000 V, 6600 V, or higher voltage motors? If you use the table your short circuit rating will be way off.
That’s when you must go by motor name plate data, period. Technically using the FLC/FLA method is wrong when you have an actual name plate rated current. But there is wisdom in practice.
By the way two gotchas on above NEMA motors. First is that with these motors the rotor thermal capacity is lower than the stator thermal capacity. For this reason thermal overload protection is not enough. You must also provide stall protection. This is non-optional protection. The best overload relays have a “learning” mode for stall protection and automatically lower the trip setting based on actual startup times of the last few starts.
Second, you can’t get away with symmetrical cool down times. Motor cool down times are much longer when the motor is off compared to when it is running. So use RTDs or adjust the hot/cold ratio appropriately.
Third and this is more of an optimization is that on most class E2 overload relays you need to set up the relay to do short circuit protection using the contactor. So for 6xFLA or higher, trip the contactor. BUT also you need to set up a second protection to inhibit the contactor from opening if the short circuit current exceeds the contactor rated interrupting current and let the fuses take those large short circuits.
Hence the reason for using advanced overload relays such as Toshiba RX or its many private labeled versions or an SEL 749 or 710 if you go top of the line. I’ve seen a lot of older Square D starters that try to get away with a bimetallic overload and a Crompton or Palladin or Carlo Gavazzi overcurrent relay for stall protection but this ignores hot/cold thermal curves.
Don’t forget the rating system on R rated fuses is pure garbage. The R rating has nothing to do with amperage.
I understand your question and don't see where the Code addresses it directly.