In reply to CyberTaff:
They are sport grades. Its just a way to sub divide the number. So 5a is easy grade 5, 5b is mid grade 5 and 5c is 5+. Im currently in kalymnos sport mecca and here the grade 4s and
5s are subdivided to 4a,b,c 5a,b,c just like the 6s and 7s always are in sport crags. The french crags just seem to prefer using + symbol on 4 and 5s.