US Core Implementation Guide
8.0.1 - STU 8

US Core Implementation Guide, published by HL7 International / Cross-Group Projects. This guide is not an authorized publication; it is the continuous build for version 8.0.1 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/US-Core/ and changes regularly. See the Directory of published versions

## Extension: US Core Direct email Extension

Official URL: http://hl7.org/fhir/us/core/StructureDefinition/us-core-direct | Version: 8.0.1
Standards status: Trial-use | Maturity Level: 3 | Computable Name: USCoreDirectEmailExtension
Other Identifiers: OID:2.16.840.1.113883.4.642.40.2.42.22
Copyright/Legal: Used by permission of HL7 International, all rights reserved Creative Commons License

This email address is associated with a "Direct Secure Messaging" service. This extension can only be used on contact points where the system = 'email'

Context of Use

This extension may be used on the following element(s)

- Element ID: `ContactPoint`

Usage info

Usages:

- Examples for this Extension: Practitioner/practitioner-2

You can also check for usages in the FHIR IG Statistics

Changes since version 7.0.0:

- No changes

### Formal Views of Extension Content

Description of Profiles, Differentials, Snapshots, and how the XML and JSON presentations work.

- Differential Table
- Snapshot Table
- Statistics/References
- All

This structure is derived from Extension

Name | Flags | Card. | Type | Description & Constraints Filter: Bindings Constraints Obligations
--- | --- | --- | --- | ---
Extension |  | 0..1 | Extension | Email is a "Direct" email
url |  | 1..1 | uri | "http://hl7.org/fhir/us/core/StructureDefinition/us-core-direct"
value[x] |  | 1..1 | boolean | Value of extension
Documentation for this format

Name | Flags | Card. | Type | Description & Constraints Filter: Bindings Constraints Obligations
--- | --- | --- | --- | ---
Extension |  | 0..1 | Extension | Email is a "Direct" email
id |  | 0..1 | string | Unique id for inter-element referencing
extension |  | 0..* | Extension | Additional content defined by implementations Slice: Unordered, Open by value:url
url |  | 1..1 | uri | "http://hl7.org/fhir/us/core/StructureDefinition/us-core-direct"
value[x] |  | 1..1 | boolean | Value of extension
Documentation for this format

This structure is derived from Extension

Summary

Simple Extension with the type boolean: This email address is associated with a "Direct Secure Messaging" service. This extension can only be used on contact points where the system = 'email'

Maturity: 3

Differential View

This structure is derived from Extension

Name | Flags | Card. | Type | Description & Constraints Filter: Bindings Constraints Obligations
--- | --- | --- | --- | ---
Extension |  | 0..1 | Extension | Email is a "Direct" email
url |  | 1..1 | uri | "http://hl7.org/fhir/us/core/StructureDefinition/us-core-direct"
value[x] |  | 1..1 | boolean | Value of extension
Documentation for this format

Snapshot View

Name | Flags | Card. | Type | Description & Constraints Filter: Bindings Constraints Obligations
--- | --- | --- | --- | ---
Extension |  | 0..1 | Extension | Email is a "Direct" email
id |  | 0..1 | string | Unique id for inter-element referencing
extension |  | 0..* | Extension | Additional content defined by implementations Slice: Unordered, Open by value:url
url |  | 1..1 | uri | "http://hl7.org/fhir/us/core/StructureDefinition/us-core-direct"
value[x] |  | 1..1 | boolean | Value of extension
Documentation for this format

This structure is derived from Extension

Summary

Simple Extension with the type boolean: This email address is associated with a "Direct Secure Messaging" service. This extension can only be used on contact points where the system = 'email'

Maturity: 3

Other representations of profile: CSV, Excel, Schematron

#### Constraints

Id | Grade | Path(s) | Description | Expression
ele-1 | error | **ALL** elements | All FHIR elements must have a @value or children | `hasValue() or (children().count() > id.count())`
ext-1 | error | **ALL** extensions | Must have either extensions or value[x], not both | `extension.exists() != value.exists()`