Original: The single digit group identifiers are: 0 or 1 for English-speaking countries; 2 for French-speaking countries; 3 for German-speaking countries; 4 for Japan; 5 for Russian-speaking countries, and 7 for Mainland China (excluding Hong Kong and Taiwan, which have 962+988 and 957+986 respectively).
Simplified: The group identifier code (GIC) number is 0 or 1 for English-speaking countries; 2 for French-speaking countries; 3 for German-speaking countries; 4 for Japanese; 5 for Russian, et cetera.