Unicode scalar values and UTF-8
UTF-8 encodes scalar values with a variable number of octets.
Key knowledge
UTF-8 encodes Unicode scalar values in one through four octets. Scalar values are U+0000 through U+10FFFF excluding U+D800 through U+DFFF. U+0000 through U+007F use one octet with the same values as ASCII.
Conditions and scope
- Code points and encoded octets are different units; a scalar value can require several octets.
- Surrogate encodings, overlong encodings and other invalid sequences are not valid UTF-8; decoding must handle malformed input.
Encoding definition, not all Unicode text-processing or glyph behavior.
Sources · 1
References
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Evidence and review
Checked the stated unicode scalar values and utf-8 and restrictions against the listed primary sections; exact inspected boundaries are in the author receipt.
2026-10-10 · Independent Physics and Measurement reference editor (AI editorial bounded review). Independent AI editorial review of this entry's statements, equations, applicability conditions and source coverage. Source checks apply to these claims within their stated limits.
Entry details
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- foundation-info-unicode-utf8
- Revision
- foundations-refresh.1
- Structured reference record
- Foundational reference additions