Japanese Industrial Standards (JIS) has standard JIS-C-7012 for semiconductor part numbers. The first digit denotes the p-n junction count ("3" may also denote a dual-gate FET); then follows the letter "S", then:

Then follows the Japan Electronics and Information Technology Industries Association's Electronic DEvice REgistration Center (JEITA-EDEREC)-assigned part number, optionally followed by suffixes (such as "A", "B", "C", or "R", "O", "BL", standing for "Red", "Orange", "Blue" etc.) to denote variants, such as tighter h_FE (gain) groupings.^[1][2]

Example: 2SD965, but sometimes the "2S" prefix is not marked on the package – a 2SD965 might only be marked "D965"; a 2SC1815 might be listed by a supplier as simply "C1815", thus possibly creating confusion with Pro Electron abbreviated markings, because a transistor marked "D965" might either be a 2SD965 or a BD965.