Original: The numbering scheme follows that of the International Numbering System (INS) as determined by the Codex Alimentarius committee though only a subset of the INS additives are approved for use in the European Union.
Simplified: The numbering scheme follows that of the International Numbering System (INS) as determined by the Codex Alimentarius committee. Only a subset of the INS additives are approved for use in the European Union, the 'E' prefix which stands for Europe.