This abbreviation is RO.
After ISO 639-1 (alpha-2 code): ro After ISO 639-2 (alpha-3 code): rum
ro
RO
The abbreviation of numéro is no.
RO is Romania.
It is not a change but a three letter alternative imposed by ISO and unfortunately accepted by some idiots from Romania: The two letters code is RO: after ISO 3166-1 alpha 2. The three letters code is ROU: after ISO 3166-1 alpha 3.
YE is the country abbreviation for Yemen.
Country Abbreviation for Nassau, Bahamas
The country with the abbreviation MOR is Morocco.
El is the country abbreviation for the country of El Salvador.
should the abbreviation for country club be c.c.?