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### 4.3 Identifiers

- Which additional multibyte characters may appear in identifiers and their correspondence to universal character names (6.4.2).
- The number of significant initial characters in an identifier (5.2.4.1, 6.4.2).

  For internal names, all characters are significant. For external names, the number of significant characters are defined by the linker; for almost all targets, all characters are significant.