Examples
Worked examples
- Is an instance
550e8400-e29b-41d4-a716-446655440000 (a v4 UUID).
- Is an instance
urn:uuid:f47ac10b-58cc-4372-a567-0e02b2c3d479 (a UUID expressed as a URN).
Counter-examples
Looks similar, but isn't
- Not an instance
An ORCID iD has only 64 bits of randomness in a different format and is not a UUID.
- Not an instance
A DOI's suffix is not a UUID.
Editorial commentary
UUIDs come in several variants and versions: v1 (time + MAC), v3 and v5 (namespace + name, hashed), v4 (random), and v7 (time-ordered, RFC 9562). They are widely used as internal database keys, file identifiers, and as URN namespace identifiers (urn:uuid:…). UUIDs are not human-meaningful and are typically opaque; resolution to a useful resource requires an external service or table lookup.
References
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Also known as
Universally Unique Identifier
Machine-readable encodings
Use in your systems
xml
<role vocab="credit"
vocab-identifier="https://casrai.org/dictionary/"
vocab-term="UUID"
vocab-term-identifier="https://casrai.org/dictionary/term/uuid" />json
{
"@context": "https://schema.org",
"@type": "DefinedTerm",
"name": "UUID",
"identifier": "https://casrai.org/dictionary/term/uuid",
"description": "Universally Unique Identifier (RFC 4122 / ISO/IEC 9834-8), a 128-bit value rendered as 32 hexadecimal digits in 8-4-4-4-12 grouping, generated such that the probability of collision across independent generators is negligible.",
"inDefinedTermSet": "https://casrai.org/dictionary/domain/the-persistent-identifier-ecosystem/",
"url": "https://casrai.org/dictionary/term/uuid",
"sameAs": [
"Universally Unique Identifier"
],
"license": "https://creativecommons.org/licenses/by/4.0/"
}
