<h2>Syntaxes</h2>

The data model as described in Sections

[[[#core-data-model]]], [[[#basic-concepts]]], and

serializations are representations of thatdata modelin a specific format. This

section specifies how thedata model is realized in JSON-LDfor

Although syntacticmappings are only provided for JSON-LD, applications and

services can use anyother data representation syntax (such as XML, YAML, or

CBOR) that is capable ofbeing mapped back to `application/vc`. As the

[=verification=] and [=validation=] requirements are defined in terms of

thedata model, all serialization syntaxes have to be deterministically

translatedto the data model for processing, [=validation=], or comparison.

The data model as described in Sections [[[#core-data-model]]],

[[[#basic-concepts]]],and[[[#advanced-concepts]]] is the canonical structural

section specifies how thedata modelis serialized in JSON-LD for

`application/vc` and `application/vp`, thebase media typesfor [=verifiable

mappings are only provided for JSON-LD, applications and services can use any

other data representation syntax (such as XML, YAML, or CBOR) that is capable of

being mapped back to `application/vc` or `application/vp`. As the

[=verification=] and [=validation=] requirements are defined in terms of the

data model, all serialization syntaxes have to be deterministically translated

to the data model for processing, [=validation=], or comparison.

The expected arity of the property values in this specification, and the

resulting datatype which holds those values, can vary depending on the property.

If present, the following properties are represented as a single value:

`id` [=property=]

`issuer` [=property=]

`validFrom` [=property=]

`validUntil` [=property=].

All other properties, if present, are represented as either a single value

or an array of values.

If present, the following properties are represented as a single value: `id`

(Section [[[#identifiers]]]), `issuer` (Section [[[#issuer]]]), and

`validFrom`/`validUntil` (Section [[[#validity-period]]]). All other properties,

if present, are represented as either a single value or an array of values.

<h3>JSON-LD</h3>

JSON-LD is a JSON-based format [[!JSON-LD11]] used to serialize

This specification uses [[[JSON-LD11]]] to serialize the data model described in

this specification. JSON-LD is useful because it enables the expression of the

<ahref="#core-data-model">graph-based data model</a> on which [=verifiable

credentials=] are based,

<ahref="https://en.wikipedia.org/wiki/Semantic_technology">machine-readable

semantics</a>, and is also useful when extending the data model (see Sections

[[[#core-data-model]]] and [[[#extensibility]]]).

JSON-LD is a JSON-based format used to serialize

<ahref="https://www.w3.org/TR/ld-glossary/#linked-data">Linked Data</a>. Linked

Data is modeled using Resource Description Framework (RDF) [[?RDF11-CONCEPTS]].

RDF is a technology for modeling graphs of statements. Each statement is a

single<i>subject→property→value</i> (also known as

<i>entity→attribute→value</i>) relationship, which is referred to as a

<a>claim</a> in this specification. JSON-LD is a technology that enables the

expression of RDF using idiomatic JSON, enabling developers familiar with JSON

to write applications that consume RDF as JSON. In general, subjects are

expressed as JSON objects with each property and value of the subject as a JSON

key and value, respectively. See

to write applications that consume RDF as JSON. See

<adata-cite="?JSON-LD11#relationship-to-rdf">Relationship of JSON-LD to RDF</a>

for more details.

JSON-LD is useful when extending the data model described in this

specification. The concept of the

<ahref="https://www.w3.org/TR/json-ld/#the-context">JSON-LD context</a>

is described in detail in the JSON-LD specification and its use is

elaborated on in Section [[[#contexts]]] and

Section [[[#extensibility]]].

Multiple contexts MAY be used or combined to express any arbitrary information

about [=verifiable credentials=] in idiomatic JSON. The base

<ahref="https://www.w3.org/TR/json-ld/#the-context">JSON-LD context</a> for

this specification is `https://www.w3.org/ns/credentials/v2`. The associated

vocabulary document for the Verifiable Credentials Data Model is available at

`https://www.w3.org/2018/credentials`.