Mobile access to Health Documents (MHD)
4.2.4-current - ci-build

Mobile access to Health Documents (MHD), published by IHE IT Infrastructure Technical Committee. This guide is not an authorized publication; it is the continuous build for version 4.2.4-current built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/IHE/ITI.MHD/ and changes regularly. See the Directory of published versions

## Data Type Profile: EntryUUIDIdentifier - Detailed Descriptions

Active as of 2025-11-03

Definitions for the IHE.MHD.EntryUUID.Identifier data type profile.

- Key Elements Table
- Differential Elements Table
- Snapshot Elements Table

Guidance on how to interpret the contents of this table can be foundhere

0. Identifier
Definition | An identifier - identifies some entity uniquely and unambiguously. Typically this is used for business identifiers.
Short | An identifier intended for computation
Control | 0..* This element is affected by the following invariants: ele-1
Is Modifier | false
Invariants | ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
2. Identifier.use
Definition | The purpose of this identifier.
Short | usual | official | temp | secondary | old (If known)
Comments | Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Control | 10..1
Binding | The codes SHALL be taken from IdentifierUse http://hl7.org/fhir/ValueSet/identifier-use|4.0.1 (required to `http://hl7.org/fhir/ValueSet/identifier-use|4.0.1` ) Identifies the purpose for this identifier, if known .
Type | code
Is Modifier | true because This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one.
Primitive Value | This primitive element may be present, or absent, or replaced by an extension
Summary | true
Requirements | Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Pattern Value | `official`
Invariants | ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
4. Identifier.system
Definition | Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Short | The namespace for the identifier value
Comments | Identifier.system is always case sensitive.
Control | 10..1
Type | uri
Is Modifier | false
Primitive Value | This primitive element may be present, or absent, or replaced by an extension
Summary | true
Requirements | 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.
Fixed Value | `urn:ietf:rfc:3986`
Example | General: http://www.acme.com/identifiers/patient
Invariants | ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count()))
6. Identifier.value
Definition | The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Short | The value that is unique
Comments | 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.
Control | 10..1
Type | string
Is Modifier | false
Primitive Value | This primitive element may be present, or absent, or replaced by an extension
Summary | true
Example | General: 123456
Invariants | ele-1: All FHIR elements must have a @value or children (hasValue() or (children().count() > id.count())) mhd-startswithuuid: value must start with urn:uuid: (`startsWith('urn:uuid:')`)

Guidance on how to interpret the contents of this table can be foundhere

0. Identifier
2. Identifier.use
Control | 1..?
Pattern Value | `official`
4. Identifier.system
Control | 1..?
Fixed Value | `urn:ietf:rfc:3986`
6. Identifier.value
Control | 1..?
Invariants | mhd-startswithuuid: value must start with urn:uuid: (`startsWith('urn:uuid:')`)

Guidance on how to interpret the contents of this table can be foundhere

0. Identifier
Definition | An identifier - identifies some entity uniquely and unambiguously. Typically this is used for business identifiers.
Short | An identifier intended for computation
Control | 0..* This element is affected by the following invariants: ele-1
Is Modifier | false
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
2. Identifier.id
Definition | Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.
Short | Unique id for inter-element referencing
Control | 0..1
Type | string
Is Modifier | false
XML Format | In the XML format, this property is represented as an attribute.
Summary | false
4. Identifier.extension
Definition | May be used to represent additional information that is not part of the basic definition of the element. 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 can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.
Short | Additional content defined by implementations
Comments | 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.
Control | 0..*
Type | Extension
Is Modifier | false
Summary | false
Alternate Names | extensions, user content
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) ext-1: Must have either extensions or value[x], not both (`extension.exists() != value.exists()`)
Slicing | This element introduces a set of slices on `Identifier.extension`. The slices areUnordered and Open, and can be differentiated using the following discriminators: value @ url
6. Identifier.use
Definition | The purpose of this identifier.
Short | usual | official | temp | secondary | old (If known)
Comments | Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.
Control | 1..1
Binding | The codes SHALL be taken from IdentifierUse (required to `http://hl7.org/fhir/ValueSet/identifier-use|4.0.1` ) Identifies the purpose for this identifier, if known .
Type | code
Is Modifier | true because This is labeled as "Is Modifier" because applications should not mistake a temporary id for a permanent one.
Primitive Value | This primitive element may be present, or absent, or replaced by an extension
Summary | true
Requirements | Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.
Pattern Value | `official`
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
8. Identifier.type
Definition | A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.
Short | Description of identifier
Comments | 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.
Control | 0..1
Binding | Unless not suitable, these codes SHALL be taken from Identifier Type Codes (extensible to `http://hl7.org/fhir/ValueSet/identifier-type|4.0.1` ) A coded type for an identifier that can be used to determine which identifier to use for a specific purpose.
Type | CodeableConcept
Is Modifier | false
Summary | true
Requirements | Allows users to make use of identifiers when the identifier system is not known.
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
10. Identifier.system
Definition | Establishes the namespace for the value - that is, a URL that describes a set values that are unique.
Short | The namespace for the identifier value
Comments | Identifier.system is always case sensitive.
Control | 1..1
Type | uri
Is Modifier | false
Primitive Value | This primitive element may be present, or absent, or replaced by an extension
Summary | true
Requirements | 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.
Fixed Value | `urn:ietf:rfc:3986`
Example | General: http://www.acme.com/identifiers/patient
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
12. Identifier.value
Definition | The portion of the identifier typically relevant to the user and which is unique within the context of the system.
Short | The value that is unique
Comments | 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.
Control | 1..1
Type | string
Is Modifier | false
Primitive Value | This primitive element may be present, or absent, or replaced by an extension
Summary | true
Example | General: 123456
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`) mhd-startswithuuid: value must start with urn:uuid: (`startsWith('urn:uuid:')`)
14. Identifier.period
Definition | Time period during which identifier is/was valid for use.
Short | Time period when id is/was valid for use
Control | 0..1
Type | Period
Is Modifier | false
Summary | true
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)
16. Identifier.assigner
Definition | Organization that issued/manages the identifier.
Short | Organization that issued id (may be just text)
Comments | 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.
Control | 0..1
Type | Reference(Organization)
Is Modifier | false
Summary | true
Invariants | ele-1: All FHIR elements must have a @value or children (`hasValue() or (children().count() > id.count())`)