Originally Posted by ISO/IEC 14882:2003(E)
Phases of translation 2.1.1.5
Each source character set member, escape sequence, or universal-character-name in character literals and string literals is converted to a member of the execution character set (2.13.2, 2.13.4).
Character Sets 2.2.3
The basic execution character set and the basic execution wide-character set shall each contain all the members of the basic source character set, plus control characters representing alert, backspace, and carriage return, plus a null character ... The execution character set and the execution wide-character set are supersets of the basic execution character set and the basic execution wide-character set, respectively. The values of the members of the execution character sets are implementation-defined, and any additional members are locale-specific.