The technical details of an endpoint that can be used for electronic services, such as for web services providing XDS.b or a REST endpoint for another FHIR server. This may include any security context information.

The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

The only time that a resource does not have an id is when it is being submitted to the server using a create operation.

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of it's narrative along with other profiles, value sets, etc.

The base language in which the resource is written.

Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope.

This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags In their meta elements, but SHALL NOT have security labels.

An Extension

• value @ url

Identifies and conveys information about restrictions on the use or release of exchanged information, e.g. information that can only be shared under particular condition, such as a signed data use agreement between parties

An extension to indicate the specific use cases/services supported by an endpoint, e.g. “I support this implementation guide at this endpoint”

Order established by a Role, Organization... for Endpoints capable of transferring the same content

An extension to describe digital certificates

May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Identifier for the organization that is used to identify the endpoint across multiple disparate systems.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

• value @ url

Describes the status of an identifier

The purpose of this identifier.

Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.

Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.

A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.

Allows users to make use of identifiers when the identifier system is not known.

This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage. Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.

Establishes the namespace for the value - that is, a URL that describes a set values that are unique.

There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.

Identifier.system is always case sensitive.

The portion of the identifier typically relevant to the user and which is unique within the context of the system.

If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the Rendered Value extension. Identifier.value is to be treated as case sensitive unless knowledge of the Identifier.system allows the processer to be confident that non-case-sensitive processing is safe.

Time period during which identifier is/was valid for use.

Organization that issued/manages the identifier.

The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.

active | suspended | error | off | test.

This element is labeled as a modifier because the status contains codes that mark the endpoint as not currently valid.

A coded value that represents the technical details of the usage of this endpoint, such as what WSDLs should be used in what way. (e.g. XDS.b/DICOM/cds-hook).

For additional connectivity details for the protocol, extensions will be used at this point, as in the XDS example.

A friendly name that this endpoint can be referred to with.

The organization that manages this endpoint (even if technically another organization is hosting this in the cloud, it is the organization associated with the data).

This property is not typically used when searching for Endpoint resources for usage. The typical usage is via the reference from an applicable Organization/Location/Practitioner resource, which is where the context is provided. Multiple Locations may reference a single endpoint, and don't have to be within the same organization resource, but most likely within the same organizational hierarchy.

Contact details for a human to contact about the subscription. The primary use of this for system administrator troubleshooting.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

• value @ url

Time period when the contact point is to be used

Represents an external point of contact responsible for handling communications with this entity

Telecommunications form for contact point - what communications system is required to make use of the contact.

The actual contact point details, in a form that is meaningful to the designated communication system (i.e. phone number or email address).

Need to support legacy numbers that are not in a tightly controlled format.

Additional text data such as phone extension numbers, or notes about use of the contact are sometimes included in the value.

Identifies the purpose for the contact point.

Need to track the way a person uses this contact, so a user can choose which is appropriate for their purpose.

Applications can assume that a contact is current unless it explicitly says that it is temporary or old.

Specifies a preferred order in which to use a set of contacts. ContactPoints with lower rank values are more preferred than those with higher rank values.

Note that rank does not necessarily follow the order in which the contacts are represented in the instance.

Time period when the contact point was/is in use.

The interval during which the endpoint is expected to be operational.

The payload type describes the acceptable content that can be communicated on the endpoint.

The payloadFormat describes the serialization format of the data, where the payloadType indicates the specific document/schema that is being transferred; e.g. DischargeSummary or CarePlan.

The mime type to send the payload in - e.g. application/fhir+xml, application/fhir+json. If the mime type is not specified, then the sender could send any content (including no content depending on the connectionType).

Sending the payload has obvious security consequences. The server is responsible for ensuring that the content is appropriately secured.

The uri that describes the actual end-point to connect to.

For rest-hook, and websocket, the end-point must be an http: or https: URL; for email, a mailto: url, for sms, a tel: url, and for message the endpoint can be in any form of url the server understands (usually, http: or mllp:). The URI is allowed to be relative; in which case, it is relative to the server end-point (since there may be more than one, clients should avoid using relative URIs)

This address will be to the service base, without any parameters, or sub-services or resources tacked on.

E.g. for a WADO-RS endpoint, the url should be "https://pacs.hospital.org/wado-rs"

and not "https://pacs.hospital.org/wado-rs/studies/1.2.250.1.59.40211.12345678.678910/series/1.2.250.1.59.40211.789001276.14556172.67789/instances/...".

Additional headers / information to send as part of the notification.

Exactly what these mean depends on the channel type. The can convey additional information to the recipient and/or meet security requirements.