Internet Assigned Numbers Authority • Domains • Protocols • Numbers • About Semantic Definition Format (SDF) Created 2025-03-27 Last Updated 2026-02-02 Available Formats [IMG] XML [IMG] HTML [IMG] Plain text Registries Included Below • SDF Quality Names • SDF Quality Name Prefixes • sdfType Values • SDF Feature Names SDF Quality Names Registration Procedure(s) Specification Required Expert(s) Ari Keranen (primary), Michael Koster (backup) Reference [RFC9880] Available Formats [IMG] CSV Name Brief Description Reference Change Controller $comment source code comments only, no semantics [RFC9880] IETF const constant value [RFC9880] IETF contentFormat content format [RFC9880] IETF default default value [RFC9880] IETF description long description text [RFC9880] IETF enum sdfChoice limited to text strings [RFC9880] IETF exclusiveMaximum exclusive maximum for a number [RFC9880] IETF exclusiveMinimum exclusive minimum for a number [RFC9880] IETF format specific format for a text string [RFC9880] IETF items items of an array [RFC9880] IETF label short text (no constraints); defaults to key [RFC9880] IETF maxItems maximum number of items in an array [RFC9880] IETF maxLength maximum length for a text string (in characters, i.e., Unicode scalar values) [RFC9880] IETF maximum maximum for a number [RFC9880] IETF minItems minimum number of items in an array [RFC9880] IETF minLength minimum length for a text string (in characters, i.e., Unicode scalar values) [RFC9880] IETF minimum minimum for a number [RFC9880] IETF multipleOf step size of number [RFC9880] IETF nullable boolean: can the item be left out? [RFC9880] IETF observable boolean: can the item be observed? [RFC9880] IETF pattern regular expression pattern for a text string [RFC9880] IETF properties named dataqualities for type="object" [RFC9880] IETF readable boolean: can the item be read? [RFC9880] IETF required which data items are required? [RFC9880] IETF sdfChoice named dataqualities for a choice [RFC9880] IETF sdfData named dataqualities for an independent data type definition [RFC9880] IETF sdfInputData input data to an action [RFC9880] IETF sdfOutputData output data of an action or event (sdfRequired applies here) [RFC9880] IETF sdfRef sdf-pointer to definition being referenced [RFC9880] IETF sdfRequired pointer-list to declarations of required components [RFC9880] IETF sdfRequiredInputData pointer-list to declarations of required input data for an action [RFC9880] IETF sdfType more detailed information about the type of a string [RFC9880] IETF type general category of data type [RFC9880] IETF uniqueItems boolean: do the items of the array need to be all different? [RFC9880] IETF unit engineering unit and scale (per SenML registry) [RFC9880] IETF writable boolean: can the item be written to? [RFC9880] IETF SDF Quality Name Prefixes Registration Procedure(s) Expert Review Expert(s) Ari Keranen (primary), Michael Koster (backup) Reference [RFC9880] Prefix Contact Reference No registrations at this time. sdfType Values Registration Procedure(s) Specification Required Expert(s) Ari Keranen (primary), Michael Koster (backup) Reference [RFC9880] Available Formats [IMG] CSV Name Description type JSON Representation Reference Change Controller byte-string A sequence of zero or more bytes string base64url without padding [RFC 8949, Section 3.4.5.2] IETF unix-time A point in civil time [1] number POSIX time [RFC 8949, Section 3.4.2] IETF SDF Feature Names Registration Procedure(s) Specification Required Expert(s) Ari Keranen (primary), Michael Koster (backup) Reference [RFC9880] Name Brief Description Reference Change Controller No registrations at this time. Footnote [1] Note that the definition of unix-time does not imply the capability to represent points in time that fall on leap seconds. More date/time-related sdfTypes are likely to be added in the sdfType value registry. Licensing Terms