I believe janetflight is referring to the AIRLINE or carrier code, not the airport code.
As in NZ (IATA) or ANZ (ICAO) for Air New Zealand.
AeroSucre S.A. (air carrier) - IATA: 6N, ICAO: KRE
Puerto Carreno (airport) - IATA: PCR, ICAO: SKPC (But not the codes in question)
However, one typo in a footnote is not exactly "definitive" of the quality of the report. Good Lord!