The US has a tendency to approach in a slightly different manner.
ICAO Annex 14 refers.... up to three parallel runways can use L, R and C, thereafter one set is rounded to the nearest 10 degrees, the other set is rounded to the next nearest 10 degrees, (theoretically) opening up the options to have up to six parallel runways. You will run into some confusion no doubt, which is why Istanbul has used a slightly different version and uses three sets of numbers for five runways.