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- The classical US-ASCII characters (0 to 0x7f) encode as themselves, so files and strings that are encoded with ASCII values have the same encoding under both ASCII and UTF-8.
- It is easy to convert between UTF-8 and UCS-2 and UCS-4 fixed-width representations of characters.
- The lexicographic sorting order of UCS-4 strings is preserved.
- All possible 2^31 2^21 UCS codes can be encoded using UTF-8.
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Although UTF-8 originated from the Plan 9 developers [Pike 1993], Plan 9's own support covers only the low 16-bit range. In general, many "Unicode" systems support only the low 16-bit range, not the full 3121-bit ISO 10646 code space [ISO/IEC 10646:2003(E)].
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