Including minor changes: 1) Adding the deprecated: true tag within the schemas and properties of some deprecated parameters; 2) Fixing the required properties for EntityMap and ContextSourceIdentity schemas and the body requests and reponses for the related endpoint operations.

As stated by section 6.3.18 Limiting Distributed Operations of the NGSI-LD API v1.8.1 specification, the Registry API operations are always local and thus are not included. This section also add a new clause for including the HTTP Via Header (IETF RFC 7230) for all the operations over the endpoints /entities/, /types/, /attributes/, /subscriptions/, /csourceSubscriptions/, /entityOperations/, /temporal/entities/ and temporal/entityOperations/.

Including the schema and query parameter definition for format representation within /entity and /entity/temporal operations (this new parameter deprecates the options representation parameter).

Updating NGSI-LD OAS v1.8.1 operations already considered in v1.7.1: 1) Including new query parameters, some descriptions, and headers for GET operations within the following endpoints: /entities, /entities/{entityId}, /temporal/entities, and /temporal/entities/{entityId}; 2) Updating and including the definition of the new/updated query parameters within the Parameters section of the NGSI-LD OAS; 3) Including error code 504 GatewayTimeout instead of 503 ServiceUnavailable for JSON-LD Context Access Points within the DELETE /jsonldContext/{contextId} operation; 4) Including GeoJSON FeatureCollection as return data type within the HTTP 200 response body of POST /entityOperations/query operation.

Updating Query schema, including the pick, omit, datasetId, and entityMap properties, and updating the description of the attrs property (deprecated).

Updating NotificationParams schema, including the pick, omit, join, and joinLevel properties, and updating the description of the attributes property (deprecated). In addition, specifying the readOnly=true option for the output properties.

Updating Subscription.Common schema, including the localOnly and datasetId properties and updating the description of the entities property.

Reviewing and updating major changes for data types regarding Entity-Property-Relationship within the NGSI-LD OAS v1.8.1: 1) Generating new schemas for new data types: JsonProperty, ListProperty, and ListRelationship. 2) Updating the additionalProperties field within the schemas of Entity, Property, Relationship, and derives, and the referenced schemas within the AttributeFragment request body. 3) Updating the Relationship schema for considering new properties such as entity and objectType, and fixing the data type for object property. 4) Fixing minor issues: removing allOf wrapper from previousValue property of the Property schema and from value property of GeoProperty schema.

Adding a clarification within the detail property description of the ProblemDetails schema about the InvalidRequest HTTP error (6.3.20 Invalid parameters).

Removing the content for json+ld and geo MIME types of the global responses relative to errors within the NGSI-LD OAS.

Including NGSILD-Warning Header for all GET operations and for all type of HTTP responses, also for HTTP 20X responses. Adding NGSILD-Warning for the global responses of NGSI-LD OAS BadRequest, NotFound, NotImplemented, and Unprocessable.

Deleting the required statements for timerel and timeAt query parameters of 5.7.4 Query Temporal Evolution of Entities, and indicating within the description of the operation that requirements.

Removing the allOf wrapper for schemas definition when they reference to other schemas that include additional sibling descriptions, because the original schema (i.e., the reference one) is lost.

For schemas definitions with  to other schemas that include additional sibling descriptions, wrapping the  into allOf.

Fixing issues with headers definition within the operation responses on NGSI-LD OAS. Including all the possible headers within the global response defined on responses section of NGSI-LD OAS.

Adding the optional query parameter type for the selection of Entity type in additional operations as indicated in ETSI GS CIM 009 V1.7.1 (i.e., 6.5.3.1 GET /entities/{entityId}, 6.5.3.2 DELETE /entities/{entityId}, 6.5.3.3 PUT /entities/{entityId}, 6.5.3.4 PATCH /entities/{entityId}, 6.6.3.1 POST /entities/{entityId}/attrs/, 6.6.3.2 PATCH /entities/{entityId}/attrs/, 6.7.3.1 PATCH /entities/{entityId}/attrs/{attrId}, 6.7.3.2 DELETE /entities/{entityId}/attrs/{attrId}, and 6.7.3.3 PUT /entities/{entityId}/attrs/{attrId}). Adding the optional query parameter options for the selection of noOverwrite value for 6.6.3.1 POST /entities/{entityId}/attrs/ operation as indicated in ETSI GS CIM 009 V1.7.1.

Adding the HTTP 501 NotImplemented response as stated by clause 6.3.7 Representation of Entities of ETSI GS CIM 009 V1.7.1. Including the NotImplemente response for the following operations: GET /entities and GET /entities/{entityId}.

Adding the jsonldContext parameter in Subscription.Common schema as stated by clause 5.2.12 Subscription of ETSI GS CIM 009 V1.7.1.

Adding the previousValue parameter in GeoProperty schemas as stated by clause 5.2.7 GeoProperty of ETSI GS CIM 009 V1.7.1.

Adding a new schema named VocabularyProperty for the new data type considered in the clause 5.2.35 VocabularyProperty of ETSI GS CIM 009 V1.7.1.

Adding the count query parameter and NGSILD-Results-Count HTTP header for 200 response within GET /temporal/entities operation as stated by clause 6.3.13 Counting Number of Results in ETSI GS CIM 009 V1.7.1.

Updating info and externalDocs sections of the NGSI-LD OAS to indicate the version 1.7.1 of NGSI-LD API.

Updating example of custom OpenAPI schemas that are compliant with the NGSI-LD OAS for IoT sensors use case.

Removing allOf keyword for references to additional components when there are already descriptions. Including  and description fields together despite the sibling issue in OAS 3.0.3.

NGSI-LD Data Types (Schemas, Headers, and Parameters) - OAS 1.6.1

Recovering SubscriptionFragment Request Body definition. Generating a new Path common schema for URI data type in path parameters. Generating a new SystemGeneratedAttributes for grouping subschemas of system-generated temporal attributes: createdAt, modifiedAt, and deletedAt, and updating references to it. Keeping NGSILD-Warning header only for HTTP GET operations performed over the resources /entities and /entities/{entity-id}.