The 2-digit group is the first two digits (AA). ... The 6-digit group is the first six digits (AABBCC). They are similar to 10-digit Harmonized Tariff System (HTS) codes (the import codes) in that the groups are the same up to the 6-digit level. At the 10-digit level, Schedule B codes and HTS codes can be different.Feb 15, 2013