A persistent identifier for the bundle that won't change as a bundle is copied from server to server.

Persistent identity generally only matters for batches of type Document, Message, and Collection. It would not normally be populated for search and history results and servers ignore Bundle.identifier when processing batches and transactions. For Documents the .identifier SHALL be populated such that the .identifier is globally unique.

The date/time that the bundle was assembled - i.e. when the resources were placed in the bundle.

For many bundles, the timestamp is equal to .meta.lastUpdated, because they are not stored (e.g. search results). When a bundle is placed in a persistent store, .meta.lastUpdated will be usually be changed by the server. When the bundle is a message, a middleware agent altering the message (even if not stored) SHOULD update .meta.lastUpdated. .timestamp is used to track the original time of the Bundle, and SHOULD be populated.

Usage:

• document : the date the document was created. Note: the composition may predate the document, or be associated with multiple documents. The date of the composition - the authoring time - may be earlier than the document assembly time
• message : the date that the content of the message was assembled. This date is not changed by middleware engines unless they add additional data that changes the meaning of the time of the message
• history : the date that the history was assembled. This time would be used as the _since time to ask for subsequent updates
• searchset : the time that the search set was assembled. Note that different pages MAY have different timestamps but need not. Having different timestamps does not imply that subsequent pages will represent or include changes made since the initial query
• transaction | transaction-response | batch | batch-response | collection : no particular assigned meaning

The timestamp value should be greater than the lastUpdated and other timestamps in the resources in the bundle, and it should be equal or earlier than the .meta.lastUpdated on the Bundle itself.

If a set of search matches, this is the total number of entries of type 'match' across all pages in the search. It does not include search.mode = 'include' or 'outcome' entries and it does not provide a count of the number of entries in the Bundle.

Only used if the bundle is a search result set. The total does not include resources such as OperationOutcome and included resources, only the total number of matching resources.

A name which details the functional use for this link - see http://www.iana.org/assignments/link-relations/link-relations.xhtml#link-relations-1.

Note that FHIR strings SHALL NOT exceed 1MB in size

The reference details for the link.

see http://en.wikipedia.org/wiki/Uniform_resource_identifier

A series of links that provide context to this entry.

Why this entry is in the result set - whether it's included as a match or because of an _include requirement, or to convey information or warning information about the search process.

There is only one mode. In some corner cases, a resource may be included because it is both a match and an include. In these circumstances, 'match' takes precedence.

When searching, the server's search ranking score for the entry.

Servers are not required to return a ranking score. 1 is most relevant, and 0 is least relevant. Often, search results are sorted by score, but the client may specify a different sort order.

See Patient Match for the EMPI search which relates to this element.

If the ETag values match, return a 304 Not Modified status. See the API documentation for "Conditional Read".

Note that FHIR strings SHALL NOT exceed 1MB in size

Only perform the operation if the last updated date matches. See the API documentation for "Conditional Read".

Note: This is intended for where precisely observed times are required, typically system logs etc., and not human-reported times - for them, see date and dateTime (which can be as precise as instant, but is not required to be) below. Time zone is always required

Only perform the operation if the Etag value matches. For more information, see the API section "Managing Resource Contention".

Note that FHIR strings SHALL NOT exceed 1MB in size

Instruct the server not to perform the create if a specified resource already exists. For further information, see the API documentation for "Conditional Create". This is just the query portion of the URL - what follows the "?" (not including the "?").

Note that FHIR strings SHALL NOT exceed 1MB in size

The Etag for the resource, if the operation for the entry produced a versioned resource (see Resource Metadata and Versioning and Managing Resource Contention).

Etags match the Resource.meta.versionId. The ETag has to match the version id in the header if a resource is included.

The date/time that the resource was modified on the server.

This has to match the same time in the meta header (meta.lastUpdated) if a resource is included.

Digital Signature - base64 encoded. XML-DSig or a JWT.

A Signature holds an electronic representation of a signature and its supporting context in a FHIR accessible form. The signature may either be a cryptographic type (XML DigSig or a JWS), which is able to provide non-repudiation proof, or it may be a graphical image that represents a signature or a signature process. This element allows capturing signatures on documents, messages, transactions or even search responses, to support content-authentication, non-repudiation or other business cases. This is primarily relevant where the bundle may travel through multiple hops or via other mechanisms where HTTPS non-repudiation is insufficient.

The signature could be created by the "author" of the bundle or by the originating device. Requirements around inclusion of a signature, verification of signatures and treatment of signed/non-signed bundles is implementation-environment specific.