While most languages are given one code by the standard , twenty of the languages described have two three-letter codes , a `` bibliographic '' code ( ISO 639-2 \ / B ) , which is derived from the English name for the language and was a necessary legacy feature , and a `` terminological '' code ( ISO 639-2 \ / T ) , which is derived from the native name for the language .
Where two ISO 639-2 codes are given in the table , the one with the asterisk is the bibliographic code ( B code ) and the other is the terminological code ( T code ) .