The set of all characters onto which a coded character set maps integers (code positions).
For example, consider these two simple coded character sets:
Coded Character Set One: integer 0 -> the character "A" integer 1 -> the character "B"
Coded Character Set Two: integer 0 -> the character "B" integer 1 -> the character "A"
Both of these coded character sets map to the characters "A" and "B", so they have the same character repertoire. But since the mapping is different (and obviously incompatible), these are different coded character sets.