i dont think its different for every country. when you look at a markscheme for example, and you see the grade boundaries, do they say
A 63 for middle east?
A 65 for east asia?
nope, they put you 1 number for A, 1 number for C and one number for E. so i think the grade boundaries are the same worldwide, and you get that certificate i think , by getting one of the 10 highest marks, not just in your country. imagine your country had only one centre for IGs, so your just going to be competing against your centre? doesnt make sense...