Superset/Subset of Character Set in Oracle Database

Oracle defines a superset/subset pair as 2 character sets that define exactly the same characters at the same codepoints and on top of that one (and only one) of them defines some additional characters (that is the
superset).
If a character set defines the same characters (and some more) as another character set but uses different codepoints to define these characters they are NOT classed as a superset/subset pair.