The OData service generates a delta token that is issued with a normal response to an entity-set request, which retrieves delta changes from the current state of the entity set. In the user’s next request for the same entity set, the token can be included in the request context as a URI parameter.
When a delta token requests data, changed or inserted results are returned, ordered by date and time (older changes are listed first). For changed records, the result must include all changed fields, and may optionally contain additional unchanged fields from the record. If no records have been changed since the first request, the response contains no records.
If the client is capable of storing data locally, the delta token can instruct the OData service to return only new or changed data when queried for an entity set.
The method by which a delta token is issued and constructed is determined by the delta token issuer. It is typically by way of a date-time token; therefore, the delta token should be related to one specific time zone, such as UTC.