The "Language Code" is refering to the
ISO-639-2 and
ISO-639-3 Language Code.
Example : "en" for English, "fr" for French.
p : is preferred Name in this language
s : is short Name in this language
h : is historic Name in this language
c : is colloquial Name in this language
accepted pseudo language codes are : 'post' (postal codes), 'icao','iata' and 'faac' (airport codes),'abbr' (abbreviation), 'link' (link to website)