chr returns the character having the binary equivalent to n in either the database character set or the national character set.

If USING NCHAR_CS is not specified, then this function returns the character having the binary equivalent to n as a VARCHAR2 value in the database character set.

If USING NCHAR_CS is specified, then this function returns the character having the binary equivalent to n as a NVARCHAR2 value in the national character set.

For single-byte character sets, if n > 256, then Oracle returns the binary equivalent of n mod 256. For multibyte character sets, n must resolve to one entire codepoint. Invalid codepoints are not validated, and the result of specifying invalid codepoints is indeterminate.