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• Datatypes
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• Detailed Descriptions
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• Extensions
• R4 Conversions

2.1.28.0 Datatypes

Modeling and Methodology Work Group

Maturity Level: Normative

Standards Status: Partially Normative

Types Framework Cross Reference: Base Types | Datatypes | Resources | Patterns

The FHIR specification defines a set of datatypes that are used for the resource elements. There are five categories of datatypes:

1. The base abstract types that provide the foundation for all types
2. Simple / primitive types, which are single elements with a primitive value (below)
3. General-purpose complex types, which are re-usable clusters of elements (below)
4. MetaDatatypes: A set of types for use with metadata resources
5. Special purpose datatypes - defined elsewhere in the specification for specific usages: Reference, Meta, Narrative, Extension, xhtml, ElementDefinition and Dosage.

This page describes the general-purpose datatypes (categories 1 and 2).

Datatypes Summary.

Legend: see Standards Status Colors

A limited set of these datatypes may appear in extensions. All datatypes (including primitives) may have extensions, but only the following datatypes may include Modifier Extensions:

• Timing
• Dosage
• ElementDefinition

2.1.28.0.1 Primitive Types

The following table describes the primitive types that are used in this specification. Primitive types are those that specialize PrimitiveType, with a value, and no additional elements as children (though, like all types, they have id and extensions). See also the Examples.

Primitive Types
FHIR Name	Value Domain	XML Representation	JSON representation
base64Binary	A stream of bytes, base64 encoded (RFC 4648 ). base64Binary content does not include any whitespace or line feeds, but reading applications should ignore whitespace characters (per RFC 4648 )	xs:base64Binary	A JSON string - base64 content
	Regex: (?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?	XML Definition	JSON Definition
	There is no specified upper limit to the size of a binary, but systems will have to impose some implementation based limit to the size they support. This should be clearly documented, though there is no computable way for this at this time
boolean	true | false	xs:boolean, except that 0 and 1 are not valid values	JSON boolean (true or false)
	Regex: true|false	XML Definition	JSON Definition
canonical	A URI that refers to a resource by its canonical URL (resources with a url property). The canonical type differs from a uri in that it has special meaning in this specification, and in that it may have a version appended, separated by a vertical bar (|). Note that the type canonical is not used for the actual canonical URLs that are the target of these references, but for the URIs that refer to them, and may have the version suffix in them. Like other URIs, elements of type canonical may also have #fragment references. Unlike other URIs, canonical URLs are never relative - they are either absolute URIs, or fragment identifiers	xs:anyURI	A JSON string - a canonical URL
	Regex: \S*	XML Definition	JSON Definition
code	Indicates that the value is taken from a set of controlled strings defined elsewhere (see Using codes for further discussion). Technically, a code is restricted to a string which has at least one character and no leading or trailing whitespace, and where there is no whitespace other than single spaces in the contents	xs:token	JSON string
	Regex: [^\s]+( [^\s]+)* This datatype can be bound to a ValueSet	XML Definition	JSON Definition
date	A date, or partial date (e.g. just year or year + month) as used in human communication. The format is YYYY, YYYY-MM, or YYYY-MM-DD, e.g. 2018, 1973-06, or 1905-08-23. There SHALL be no timezone offset. Dates SHALL be valid dates.	union of xs:date, xs:gYearMonth, xs:gYear	A JSON string - a union of xs:date, xs:gYearMonth, xs:gYear
	Regex: ([0-9]([0-9]([0-9][1-9]|[1-9]0)|[1-9]00)|[1-9]000)(-(0[1-9]|1[0-2])(-(0[1-9]|[1-2][0-9]|3[0-1]) )?)?	XML Definition	JSON Definition
dateTime	A date, date-time or partial date (e.g. just year or year + month) as used in human communication. The format is YYYY, YYYY-MM, YYYY-MM-DD or YYYY-MM-DDThh:mm:ss+zz:zz, e.g. 2018, 1973-06, 1905-08-23, 2015-02-07T13:28:17-05:00 or 2017-01-01T00:00:00.000Z. If hours and minutes are specified, a timezone offset SHALL be populated. Actual timezone codes can be sent using the Timezone Code extension, if desired. Seconds must be provided due to schema type constraints but may be zero-filled and may be ignored at receiver discretion. Milliseconds are optionally allowed. Dates SHALL be valid dates. The time "24:00" is not allowed. Leap Seconds are allowed - see below	union of xs:dateTime, xs:date, xs:gYearMonth, xs:gYear	A JSON string - a union of xs:dateTime, xs:date, xs:gYearMonth, xs:gYear
	Regex: ([0-9]([0-9]([0-9][1-9]|[1-9]0)|[1-9]00)|[1-9]000)(-(0[1-9]|1[0-2])(-(0[1-9]|[1-2][0-9]|3[0-1]) (T([01][0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)(\.[0-9]{1,9})?)?)?(Z|(\+|-)((0[0-9]|1[0-3]):[0- 5][0-9]|14:00)?)?)?	XML Definition	JSON Definition
decimal	Rational numbers that have a decimal representation. Decimals in FHIR cannot have more than 18 digits and a decimal point. See below about the precision of the number	union of xs:decimal and xs:double (see below for limitations)	A JSON number (see below for limitations)
	Regex: -?(0|[1-9][0-9]{0,17})(\.[0-9]{1,17})?([eE][+-]?[0-9]{1,9}})?	XML Definition	JSON Definition
id	Any combination of upper- or lower-case ASCII letters ('A'..'Z', and 'a'..'z', numerals ('0'..'9'), '-' and '.', with a length limit of 64 characters. (This might be an integer, an un-prefixed OID, UUID or any other identifier pattern that meets these constraints.)	xs:string	JSON string
	Regex: [A-Za-z0-9\-\.]{1,64}	XML Definition	JSON Definition
instant	An instant in time in the format YYYY-MM-DDThh:mm:ss.sss+zz:zz (e.g. 2015-02-07T13:28:17.239+02:00 or 2017-01-01T00:00:00Z). The time SHALL specified at least to the second and SHALL include a timezone offset. Actual timezone codes can be sent using the [[[http://hl7.org/fhir/StructureDefinition/timezone extension]]], if desired. Note: This is intended for when precisely observed times are required (typically system logs etc.), and not human-reported times - for those, use date or dateTime (which can be as precise as instant, but is not required to be). instant is a more constrained dateTime	xs:dateTime	A JSON string - an xs:dateTime
	Note: This type is for system times, not human times (see date and dateTime below).
	Regex: ([0-9]([0-9]([0-9][1-9]|[1-9]0)|[1-9]00)|[1-9]000)-(0[1-9]|1[0-2])-(0[1-9]|[1-2][0-9]|3[0-1])T( [01][0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)(\.[0-9]{1,9})?(Z|(\+|-)((0[0-9]|1[0-3]):[0-5][0-9] |14:00))	XML Definition	JSON Definition
integer	A signed integer in the range −2,147,483,648..2,147,483,647 (32-bit; for larger values, use decimal)	xs:int, except that leading 0 digits are not allowed	JSON number (with no decimal point)
	Regex: [0]|[-+]?[1-9][0-9]*	XML Definition	JSON Definition
integer64	A signed integer in the range -9,223,372,036,854,775,808 to +9,223,372,036,854,775,807 (64-bit). This type is defined to allow for record/time counters that can get very large	xs:long, except that leading 0 digits are not allowed	JSON String (due to issues with precision in floating point libraries)
	Regex: [0]|[-+]?[1-9][0-9]*	XML Definition	JSON Definition
markdown	A FHIR string (see below) that may contain markdown syntax for optional processing by a markdown presentation engine, in the GFM extension of CommonMark format (see below)	xs:string	JSON string
	Regex: ^[\s\S]+$ (can't put size limit in the regex - too large)	XML Definition	JSON Definition
oid	An OID represented as a URI (RFC 3001 ); e.g. urn:oid:1.2.3.4.5	xs:anyURI	JSON string - uri
	Regex: urn:oid:[0-2](\.(0|[1-9][0-9]*))+	XML Definition	JSON Definition
string	A sequence of Unicode characters	xs:string	JSON String
	Note that strings SHALL NOT exceed 1,048,576 (1024*1024) characters in size. Because UTF-8 characters can be expressed with more than one byte, the string size may be more than 1MB. Strings SHOULD not contain Unicode character points below 32, except for u0009 (horizontal tab), u000D (carriage return) and u000A (line feed). Leading and Trailing whitespace is allowed, but SHOULD be removed when using the XML format. Note: This means that a string that consists only of whitespace could be trimmed to nothing, which would be treated as an invalid element value. Therefore strings SHOULD always contain non-whitespace content
	This datatype can be bound to a ValueSet
	Regex: ^[\s\S]+$ (see notes below)	XML Definition	JSON Definition
positiveInt	Any positive integer in the range 1..2,147,483,647	xs:positiveInteger	JSON number
	Regex: [1-9][0-9]*	XML Definition	JSON Definition
time	A time during the day, in the format hh:mm:ss. There is no date specified. Seconds must be provided due to schema type constraints but may be zero-filled and may be ignored at receiver discretion. The time "24:00" SHALL NOT be used. A timezone offset SHALL NOT be present. Times can be converted to a Duration since midnight.	xs:time	A JSON string - an xs:time
	Regex: ([01][0-9]|2[0-3]):[0-5][0-9]:([0-5][0-9]|60)(\.[0-9]{1,9})?	XML Definition	JSON Definition
unsignedInt	Any non-negative integer in the range 0..2,147,483,647	xs:nonNegativeInteger	JSON number
	Regex: [0]|([1-9][0-9]*)	XML Definition	JSON Definition
uri	A Uniform Resource Identifier Reference (RFC 3986 ). Note: URIs are case sensitive. For UUID (urn:uuid:53fefa32-fcbb-4ff8-8a92-55ee120877b7) use all lowercase	xs:anyURI	A JSON string - a URI
	Regex: \S* (This regex is very permissive, but URIs must be valid. Implementers are welcome to use more specific regex statements for a URI in specific contexts)	XML Definition	JSON Definition
	URIs can be absolute or relative, and may have an optional fragment identifier This datatype can be bound to a ValueSet
url	A Uniform Resource Locator (RFC 1738 ). Note URLs are accessed directly using the specified protocol. Common URL protocols are http{s}:, ftp:, mailto: and mllp:, though many others are defined	xs:anyURI	A JSON string - a URL
	Regex: \S*	XML Definition	JSON Definition
uuid	A UUID (aka GUID) represented as a URI (RFC 4122 ); e.g. urn:uuid:c757873d-ec9a-4326-a141-556f43239520	xs:anyURI	JSON string - uri
	Regex: urn:uuid:[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}	XML Definition	JSON Definition

Notes:

• For all the types, the XML, JSON and Turtle representations of the primitive values are the same except for different escaping in XML and JSON
• For string content, parsers and serializers MAY retain, escape or strip unescaped non-supported UNICODE characters. If the characters are retained, a subsequent application-layer process can then determine appropriate handling based on context.
• For decimal values, the XML special values INF, -INF and NaN are not allowed, and JSON is restricted to the precision limits documented in XML schema for xs:double and xs:decimal
• The precision of the decimal value has significance:
  • e.g. 0.010 is regarded as different to 0.01, and the original precision should be preserved
  • Implementations SHALL handle decimal values in ways that preserve and respect the precision of the value as represented for presentation purposes.
  • Implementations are not required to perform calculations with these numbers differently, though they may choose to do so (i.e. preserve significance).
  • See implementation comments for XML, JSON and RDF.
  • In object code, implementations that might meet this constraint are GMP implementations or equivalents to Java BigDecimal that implement arbitrary precision, or a combination of a (64 bit) floating point value with a precision field.
  • Note that large and/or highly precise values are extremely rare in medicine. One element where highly precise decimals may be encountered is the Location coordinates. Irrespective of this, the limits documented in XML Schema apply.
• Boolean values can also be represented using coded values (such as HL7 V2 Table 0136). See Observation for one such use.
• Issues with the specified regexes:
  • The regexes are provided to assist with tooling, but are informative, not normative. There are several issues with the regexes.
  • The string regex has problems with Unicode - specifically, it might or might not allow Unicode whitespace to some degree depending on Unicode support in the regex engine being used. The regexes [\r\n\t\x{0020}-\x{FFFF}]* or [\r\n\t\u0020-\uFFFF]* are better expressions of the constraints on string, but poorly supported (see Regex Tutorial for details). The string regex also applies to markdown as well. The regex does not enforce the length limit
  • The Unicode issues also apply to the regex for code.
  • The regexes should be qualified with start of string and end of string anchors based on the regex implementation used (e.g. caret '^' and dollar-sign '$' for JavaScript, POSIX, XML and XPath; '\A' and '\Z' for .NET, Java, Python and others; please verify these definitions with the regex implementation used).
  • The regexes may allow a broader set of values than are actually valid (e.g. leap years) so additional validation is always needed.
• Leap second are allowed in the datetime, instant and time types. Note, though, that many systems and libraries do not support leap seconds. Applications reading times SHOULD accept and handle leap seconds gracefully, and applications producing them MAY choose to avoid encoding leap seconds.
• About the id datatype:
  • Ids are case sensitive. UUIDs SHALL be sent using lowercase letters.
  • The ID type includes identifiers consistent with ISO 18232 , but also includes other identifier formats as well, and is not case insensitive like ISO 18232.
  • In a typical FHIR URL, like http://example.com/fhir/Patient/1234, the last part "1234" (highlighted in red) is the part that is an id datatype.
  • A full UUID is a uri, not an id. UUIDs in URIs SHALL also be represented in lowercase (urn:uuid:59bf0ef4-e89c-4628-9b51-12ae3fdbe22b).
• About the uri, url and canonical datatypes:
  • They all contain URIs, but differ in how applications resolve the reference.
  • Although the url and canonical are specializations of uri, they are never substituted for each other.
  • They are all case sensitive for comparison purposes. Applications SHOULD not create URIs that only differ by case.
  • A general URI may be either a URL or a canonical URL or some other kind of URI.
• About the markdown datatype:
  • Markdown is a string, and subject to the same rules (e.g. length limit, valid characters)
  • This specification requires and uses the GFM (Github Flavored Markdown) extensions on CommonMark format, with the exception of support for inline HTML which is not supported.
  • Processors SHALL treat embedded XML tags as string content, not as tags. This may be done by pre-processing and escaping any ">" characters preceding character content (">" becomes "\>") before processing the content or by using a markdown processor-specific flag that accomplishes the same effect. This means that HTML content cannot be embedded in markdown to influence rendering.
  • Systems are not required to have markdown support, so the content of a string should be readable without markdown processing, per markdown philosophy.
  • Converting an element that has the type string to markdown in a later version of this FHIR specification is considered a non-breaking change for elements with a single type. It is a breaking change for multi-type/choice elements because the type name is reflected in the element name. (Adding markdown as an additional choice to a multi-type element is not a breaking change). The impact of a lack of escaping on existing string data on safe rendering should be considered in evaluating changes from string to markdown - see next bullet.
  • WARNING: Because markdown renderers will interpret certain characters as formatting characters and strip them from the display, it is essential that systems transmitting plain string data in a markdown field take steps to appropriately escape the string to avoid loss of information when rendering for human display.

Implementation Note: A simple way to convert plain text to be safe as markdown is to prefix any of the characters *, &, #, [, <, >, and ` with a backslash (\). When presenting markdown as plain text, implementers may wish to reverse this transform.

2.1.28.0.1.1 Representations in XML, JSON, and Turtle

All elements using these primitive types may have one or more of a value as described above, an internal identity (e.g. xml:id), and extensions. For an example, take an element of name "count" and type "integer".

XML

The value is represented in XML as an attribute named "value":

  <count value="2"/>

The full representation, with id, extensions and value:

  <count id="a1" value="2">
    <extension url="...">
      <valueXX.../>
    </extension>
  </count>

JSON

In JSON, for convenience, the value is represented as the property itself:

  "count" : 2

The full representation, with id, extensions and value, showing the id and extensions in the sibling property:

  "count" : 2
  "_count" : {
    "id" : "a1",
    "extension" : [{
      "url" : "...",
      "valueXXX" : "...."
    }]
  }

RDF

The value is represented in RDF as a relationship with the URI "http://hl7.org/fhir/value". Using the normal prefix, this becomes:

  fhir:Type.count [ fhir:value "2"^^xsd:integer ]

For the types date and DateTime, the type must be specified explicitly. For all other types, it is optional. The full representation, with id, extensions and value:

  fhir:Type.count [
    Element.id "a1";
    fhir:value "2"^^xsd:integer;
    Element.extension [
      fhir:Extension.url "..";
      fhir:Extension.valueXX...
    ]
  ]

For additional details, see the XML, JSON and Turtle format definitions. When the value is missing, and there are no extensions, the element is not represented at all. This means that in xml, attributes are never present with a length of 0 (value=""), and properties are never a 0 length string or null in JSON ("name" : "" is not valid). (note: there is one specific use of the null in the JSON representation).

According to XML schema, leading and trailing whitespace in the value attribute is ignored for the types boolean, integer, decimal, base64Binary, instant, uri, date, dateTime, oid, and uri. Note that this means that the schema aware XML libraries give different attribute values to non-schema aware libraries when reading the XML instances. For this reason, the value attribute for these types SHOULD not have leading and trailing spaces. String values should only have leading and trailing spaces if they are part of the content of the value. In JSON and Turtle whitespace in string values is always significant. Primitive types other than string SHALL NOT have leading or trailing whitespace.

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2.1.28.0.2 Complex Types

In XML, these types are represented as XML Elements with child elements with the name of the defined elements of the type. The name of the element is defined where the type is used. In JSON, the datatype is represented by an object with properties named the same as the XML elements. Since the JSON representation is almost exactly the same, only the first example has an additional explicit JSON representation.

Complex datatypes may be "profiled". A Structure Definition or type "constraint" makes a set of rules about which elements SHALL have values and what the possible values are.

UML Diagrams of the Datatypes

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2.1.28.0.3 Attachment

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

This type is for containing or referencing attachments - additional data content defined in other formats. The most common use of this type is to include images or reports in some report format such as PDF. However, it can be used for any data that has a MIME type.

The actual content of an Attachment can be conveyed directly using the data element or a URL reference can be provided. If both are provided, the reference SHALL point to the same content as found in the data. The reference can never be reused to point to some different data (i.e. the reference is version specific). The URL reference SHALL point to a location that resolves to actual data; some URIs such as cid: meet this requirement. If the URL is a relative reference, it is interpreted in the same way as a resource reference.

The contentType element SHALL always be populated when an Attachment contains data, and MAY be populated when there is a url. It can include charset information and other mime type extensions as appropriate. If there is no character set in the contentType then the correct course of action is undefined, though some media types may define a default character set and/or the correct character set may be able to be determined by inspection of the content.

The hash is included so that applications can verify that the content returned by the URL has not changed. The hash and size relate to the data before it is represented in base64 form. The hash is not intended to support digital signatures. Where protection against malicious threats a digital signature should be considered, see Provenance.signature for mechanism to protect a resource with a digital signature.

Attachment data are not constrained, and therefore can be of any content type and encoding. Therefore extra care needs to be taken to validate the content against malicious or malformed content. For more details see Security of Narrative.

In many cases where Attachment is used, the cardinality is >1. A valid use of repeats is to convey the same content in different mime types and languages. Guidance on the meaning of repeating elements SHALL be provided in the definition of the repeating resource element or extension that references this type. The language element describes the language of the attachment using the codes defined in BCP 47 .

Attachment is used in the following places: RelatedArtifact, AdministrableProductDefinition, BiologicallyDerivedProduct, BodyStructure, Citation, Claim, ClaimResponse, Communication, CommunicationRequest, Consent, Contract, Device, DeviceDefinition, DiagnosticReport, DocumentReference, ExplanationOfBenefit, HealthcareService, Library, ManufacturedItemDefinition, MedicationKnowledge, MedicinalProductDefinition, MolecularSequence, NutritionProduct, Observation, PackagedProductDefinition, Patient, Person, Practitioner, Questionnaire, QuestionnaireResponse, RelatedPerson, SubstanceDefinition, SubstanceNucleicAcid, SubstancePolymer and SubstanceProtein

2.1.28.0.4 Coding

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A Coding is a representation of a defined concept using a symbol from a defined "code system" - see Using Codes in resources for more details.

This datatype can be bound to a ValueSet.

The meaning of the Coding is defined by the code. The system provides the source of the definition of the code, along with an optional version reference. The display is a human display for the text defined by the system - it is not intended for computation.

The system is an absolute URI that identifies the code system that defines the code. Choosing the correct system is important; for more information about the code system URI, read Managing Terminology System URIs. If the code is taken from a CodeSystem resource, CodeSystem.url is the correct value for the system element. Resolvable URLs are generally preferred by implementers over non-resolvable URNs, particularly opaque URNs such as OIDs (urn:oid:) or UUIDs (urn:uuid:). The system URI SHALL NOT contain a reference to a value set (e.g. ValueSet.url), since value sets just define the set of codes which are intended for use in a specific context, not the meaning of the codes themselves.

A code system version may also be supplied. If the meaning of codes within the code system is consistent across releases, this is not required. The version SHOULD be exchanged when the system does not maintain consistent definitions across versions. Note that the following systems SHOULD always have a version specified:

• National releases of SNOMED CT (consistency of definitions varies amongst jurisdictions, and some jurisdictions may make their own rules on this)
• Various versions of ICD (note: the major releases are labeled as different code systems altogether, but there is variation within versions)

More generally, any classification (e.g. a code system that includes concepts with relative definitions such as "not otherwise coded" will require a version. See the discussion of code system versions in the Code System resource for further discussion on versioning.

If present, the code SHALL be a syntactically correct symbol as defined by the system. In some code systems such as SNOMED CT, the symbol may be an expression composed of other predefined symbol (e.g. post-coordination). Note that codes are case sensitive unless specified otherwise by the code system. The display is a text representation of the code defined by the system and is used to display the meaning of the code by an application that is not aware of the system.

If the 'display' element is populated, the string used in display SHALL be one of the display strings defined for that code by the code system. Code systems may define multiple display strings for a single code, by use of:

• CodeSystem.concept.display
• CodeSystem.concept.designation.value (including in supplements)

Note that displays defined in value sets (ValueSet.include.concept.display and ValueSet.include.concept.designation.value) are not allowed in Coding.display.

If one of the available display strings is labeled as preferred, it SHOULD be used (note that CodeSystem.concept.display is preferred for the base resource language if it is populated, but other display strings may be preferred in other languages, or for other usages). If the code system does not define a text representation for display (e.g. SNOMED CT Expressions) then the 'display' element cannot be populated, and the meaning of the code won't be accessible to systems that don't understand the code expression.

In some cases, the system might not be known - only the code is known. In this case, no useful processing of the code may be performed unless the system can be safely inferred by the context. This practice should be avoided where possible, as information sharing in a wider context is very likely to arise eventually, and codes cannot be used in the absence of a known system.

If the system is present, and there is no code, then this is understood to mean that there is no suitable code in the system in which to represent the concept. The implication of this is that implementers SHOULD never provide a system without a code unless this is the intended meaning AND it is appropriate for the code system and version. (E.g. the code system does not have an 'OTHER' concept.) This approach cannot be used if an appropriate code might exist within the code system but does not exist within the bound ValueSet.

If two codings have the same system, version and code then they have the same meaning. If the version information is missing, or the system, version or the code elements differ, then how the codes are related can only be determined by consulting the definitions of the system(s) and any mappings available.

A coding may be marked as a "userSelected" if a user selected the particular coded value in a user interface (e.g. the user selects an item in a pick-list). If a user selected coding exists, it is the preferred choice for performing translations etc.

Coding is used in the following places: Meta, DataRequirement, ElementDefinition, VirtualServiceDetail, UsageContext, Signature, CodeableConcept, ActivityDefinition, ActorDefinition, Appointment, AuditEvent, BiologicallyDerivedProduct, CanonicalResource, CapabilityStatement, ChargeItemDefinition, Citation, CodeSystem, CompartmentDefinition, ConceptMap, ConditionDefinition, Consent, Contract, DeviceDefinition, DocumentReference, EventDefinition, Evidence, EvidenceVariable, ExampleScenario, ExplanationOfBenefit, GraphDefinition, ImagingSelection, ImagingStudy, ImplementationGuide, InventoryItem, Library, Location, Measure, MedicinalProductDefinition, MessageDefinition, MessageHeader, NamingSystem, ObservationDefinition, OperationDefinition, Permission, PlanDefinition, Questionnaire, QuestionnaireResponse, Requirements, SearchParameter, SpecimenDefinition, StructureDefinition, StructureMap, Subscription, SubscriptionTopic, TerminologyCapabilities, TestPlan, TestScript and ValueSet

Implementation Note: This specification defines two types for representing coded values:

• Coding: a simple direct reference to a code defined by a code system
• CodeableConcept: a text description and/or a list of Codings (i.e. a list of references to codes defined by code systems)

The Coding datatype corresponds to the simple case of selecting a single code from a code list. However, this type is rarely used in the FHIR specifications; long experience with exchanging coded values in HL7 shows that in the general case, systems need to able to exchange multiple translation codes, and/or an original text.

The Coding datatype is used directly when there is certainty that the value must be selected directly from one of the available codes, and the list of possible codes is agreed to by all participants. This is not usually the case in the context of FHIR - general interoperability - so Coding is mostly used in extensions, which are usually intended to be defined for a well-controlled context of use.

2.1.28.0.5 CodeableConcept

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A CodeableConcept represents a value that is usually supplied by providing a reference to one or more terminologies or ontologies but may also be defined by the provision of text. This is a common pattern in healthcare data.

This datatype can be bound to a ValueSet.

Additional Codes

More than one code may be used in CodeableConcept. The concept may be coded multiple times in different code systems (or even multiple times in the same code systems, where multiple forms are possible, such as with SNOMED CT). Each coding (also referred to as a 'translation') is a representation of the concept as described above and may have slightly different granularity due to the differences in the definitions of the underlying codes. There is no meaning associated with the ordering of coding within a CodeableConcept. A typical use of CodeableConcept is to send the local code that the concept was coded with, and also one or more translations to publicly defined code systems such as LOINC or SNOMED CT. Sending local codes is useful and important for the purposes of debugging and integrity auditing.

For example, many qualitative laboratory test results values are typically represented with coded presence/absence concepts. Using the coded value for 'negative' with a standard SNOMED CT code translation, valueCodeableConcept would be:

	"valueCodeableConcept": {
		"coding": [
			{
				"system": "http://snomed.info/sct",
				"code": "260385009",
				"display": "Negative"
			}, {
				"system": "https://acme.lab/resultcodes",
				"code": "NEG",
				"display": "Negative"
			}
		],
		"text": "Negative for Chlamydia Trachomatis rRNA"
	}

	

Note that these concepts may be cross mapped using the ConceptMap resource instead of or in addition to being represented as translations directly in the in CodeableConcept.

Using Text in CodeableConcept

The text is the representation of the concept as entered or chosen by the user, and which most closely represents the intended meaning of the user or concept. Very often the text is the same as a display of one of the codings. One or more of the codings may be flagged as the user selected code - the code or concept that the user actually selected directly. Note that in all but a few cases, only one of the codings may be flagged as the coding.userSelected = true - the code or concept that the user actually selected directly. If more than one code is marked as user selected, this means the user explicitly chose multiple codes. When none of the coding elements is marked as user selected, the text (if present) is the preferred source of meaning. Even if a coding is flagged as user-selected, it is good practice to put the specific text the user chose in CodeableConcept.text.

A free text only representation of the concept without any coding elements is permitted if there is no appropriate code and only free text is available (and not prohibited by the implementation). For example, using text only, the Observation.valueCodeableConcept element would be:

	"valueCodeableConcept": {
		"text": "uncoded free text result"
	}

			

CodeableConcept is used in the following places: DataRequirement, Dosage, MonetaryComponent, MarketingStatus, Identifier, TriggerDefinition, RelatedArtifact, ProductShelfLife, UsageContext, CodeableReference, Timing, ExtendedContactDetail, Account, ActivityDefinition, ActorDefinition, AdministrableProductDefinition, AdverseEvent, AllergyIntolerance, Appointment, AppointmentResponse, ArtifactAssessment, AuditEvent, Basic, BiologicallyDerivedProduct, BiologicallyDerivedProductDispense, BodyStructure, CanonicalResource, CapabilityStatement, CarePlan, CareTeam, ChargeItem, ChargeItemDefinition, Citation, Claim, ClaimResponse, ClinicalImpression, ClinicalUseDefinition, CodeSystem, Communication, CommunicationRequest, Composition, ConceptMap, Condition, ConditionDefinition, Consent, Contract, Coverage, CoverageEligibilityRequest, CoverageEligibilityResponse, DetectedIssue, Device, DeviceAssociation, DeviceDefinition, DeviceDispense, DeviceMetric, DeviceRequest, DeviceUsage, DiagnosticReport, DocumentReference, Encounter, EncounterHistory, Endpoint, EpisodeOfCare, EventDefinition, Evidence, EvidenceReport, EvidenceVariable, ExampleScenario, ExplanationOfBenefit, FamilyMemberHistory, Flag, FormularyItem, GenomicStudy, Goal, GraphDefinition, Group, GuidanceResponse, HealthcareService, ImagingSelection, ImagingStudy, Immunization, ImmunizationEvaluation, ImmunizationRecommendation, ImplementationGuide, Ingredient, InsurancePlan, InventoryItem, InventoryReport, Invoice, Library, List, Location, ManufacturedItemDefinition, Measure, MeasureReport, Medication, MedicationAdministration, MedicationDispense, MedicationKnowledge, MedicationRequest, MedicationStatement, MedicinalProductDefinition, MessageDefinition, MessageHeader, MetadataResource, MolecularSequence, NamingSystem, NutritionIntake, NutritionOrder, NutritionProduct, Observation, ObservationDefinition, OperationDefinition, OperationOutcome, Organization, OrganizationAffiliation, PackagedProductDefinition, Patient, PaymentNotice, PaymentReconciliation, Permission, Person, PlanDefinition, Practitioner, PractitionerRole, Procedure, Provenance, Questionnaire, RegulatedAuthorization, RelatedPerson, RequestOrchestration, Requirements, ResearchStudy, ResearchSubject, RiskAssessment, Schedule, SearchParameter, ServiceRequest, Slot, Specimen, SpecimenDefinition, StructureDefinition, StructureMap, SubscriptionStatus, SubscriptionTopic, Substance, SubstanceDefinition, SubstanceNucleicAcid, SubstancePolymer, SubstanceProtein, SubstanceReferenceInformation, SubstanceSourceMaterial, SupplyDelivery, SupplyRequest, Task, TerminologyCapabilities, TestPlan, TestScript, Transport, ValueSet, VerificationResult and VisionPrescription

2.1.28.0.6 Quantity

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A measured amount (or an amount that can potentially be measured).

This datatype can be bound to a ValueSet.

The value contains the numerical value of the quantity, including an implicit precision. If no comparator is specified, the value is a point value (i.e. '='). The comparator element can never be ignored.

The unit element contains a displayable unit that defines what is measured. The unit may additionally be coded in some formal way using the code and the system (see Coding for further information about how to use the system element).

If the unit can be coded in UCUM and a code is provided, it SHOULD be a UCUM code. If a UCUM unit is provided in the code, then a canonical value can be generated for purposes of comparison between quantities. Note that the unit element will often contain text that is a valid UCUM unit, but it cannot be assumed that the unit actually contains a valid UCUM unit.

Quantity is used in the following places: Count, Ratio, ElementDefinition, Distance, Age, Duration, UsageContext, AdministrableProductDefinition, ArtifactAssessment, AuditEvent, BiologicallyDerivedProduct, BodyStructure, ChargeItem, Claim, ClaimResponse, ConceptMap, ConditionDefinition, Contract, Device, DeviceDefinition, DeviceMetric, DeviceRequest, Evidence, EvidenceReport, EvidenceVariable, ExplanationOfBenefit, Goal, Group, Ingredient, InsurancePlan, InventoryItem, InventoryReport, ManufacturedItemDefinition, MeasureReport, Medication, MedicationKnowledge, MedicinalProductDefinition, Observation, PackagedProductDefinition, PlanDefinition, Questionnaire, ServiceRequest, SubstanceDefinition, SubstancePolymer, SubstanceReferenceInformation and SupplyRequest

2.1.28.0.6.1 Defined Variations on Quantity

There are several additional datatypes that are specializations of Quantity that only introduce new restrictions on the existing elements defined as part of the Quantity datatype.

2.1.28.0.6.1.1 Distance

Type Name	Rules	Formal Definitions
Distance	id Level Location Description Expression  dis-1 Rule (base) There SHALL be a code if there is a value and it SHALL be an expression of length. If system is present, it SHALL be UCUM. (code.exists() or value.empty()) and (system.empty() or system = %ucum) Terminology Bindings Path ValueSet Type Documentation Distance CommonUCUMCodesForDistance Extensible Unified Code for Units of Measure (UCUM). This value set includes all common UCUM codes used for distance - that it is, all commonly used units which have the same canonical unit as 'm' (meter)   All UCUM Expression for Distance maximum	XML, JSON
	Usage: (not used as yet)
	Implementation Note: If the duration value is specified as a whole number (e.g. 1 month), then when the duration is added or subtracted to a given date(time), the outcome should be rounded to the nearest natural calendar division - e.g. Feb. 1 + 1 mo = March 1, not March 2 or 3 (since 1 month in is defined in UCUM as 30 days).

2.1.28.0.6.1.2 Distance

Age	id Level Location Description Expression  age-1 Rule (base) There SHALL be a code if there is a value and it SHALL be an expression of time. If system is present, it SHALL be UCUM. If value is present, it SHALL be positive. (code.exists() or value.empty()) and (system.empty() or system = %ucum) and (value.empty() or value.hasValue().not() or value > 0) Terminology Bindings Path ValueSet Type Documentation Age CommonUCUMCodesForAge Extensible Unified Code for Units of Measure (UCUM). This value set includes all common UCUM codes used for Age - that it is, all commonly used units which have the same canonical unit as 'a' (year)   All UCUM Expression for Time maximum	XML, JSON
Note: Age intentionally carries the semantics of a duration of time during which an organism (or a process) has existed.
	Usage: ActivityDefinition, AllergyIntolerance, Condition, FamilyMemberHistory, PlanDefinition, Procedure and RequestOrchestration

2.1.28.0.6.1.3 Count

Count	id Level Location Description Expression  cnt-3 Rule (base) There SHALL be a code with a value of "1" if there is a value. If system is present, it SHALL be UCUM. If present, the value SHALL be a whole number. (code.exists() or value.empty()) and (system.empty() or system = %ucum) and (code.empty() or code = '1') and (value.empty() or value.hasValue().not() or value.toString().contains('.').not())	XML, JSON
	Usage: Device

2.1.28.0.6.1.4 Duration

Duration	id Level Location Description Expression  drt-1 Rule (base) There SHALL be a code if there is a value and it SHALL be an expression of time. If system is present, it SHALL be UCUM. code.exists() implies ((system = %ucum) and value.exists()) Terminology Bindings Path ValueSet Type Documentation Duration CommonUCUMCodesForDuration Extensible Unified Code for Units of Measure (UCUM). This value set includes all common UCUM codes used for Duration - that it is, all commonly used units which have the same canonical unit as 'a' (year)   All UCUM Expression for Time maximum	XML, JSON
Note: Duration intentionally carries the semantics of a length of time.
	Usage: DataRequirement, ProductShelfLife, Timing, ActivityDefinition, AdministrableProductDefinition, Device, Encounter, EncounterHistory, Goal, InventoryItem, MeasureReport, MedicationKnowledge, MedicationRequest, PlanDefinition, RequestOrchestration, Specimen and SpecimenDefinition

In addition to the specializations, there is one constraint on Quantity used in several resources:

2.1.28.0.6.1.5 Simple Quantity

Profile Name	Rules	Formal Definitions
Simple Quantity	id Level Location Description Expression sqty-1 Rule (base) The comparator is not used on a SimpleQuantity comparator.empty()	XML, JSON
	Usage: Dosage, RatioRange, SampledData, Ratio, Range, ActivityDefinition, BiologicallyDerivedProductDispense, Claim, ClaimResponse, Contract, Coverage, CoverageEligibilityRequest, DeviceDispense, Evidence, ExplanationOfBenefit, Immunization, InventoryItem, MedicationAdministration, MedicationDispense, MedicationKnowledge, MedicationRequest, NutritionIntake, NutritionOrder, NutritionProduct, Observation, QuestionnaireResponse, Specimen, SpecimenDefinition, Substance, SupplyDelivery and VisionPrescription

Note that the constraint is different from the other specializations of Quantity because it is not a type, just rules applied where the Quantity type is used. There's another constraint - see Money immediately below.

2.1.28.0.7 Money

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

An amount of currency.

The value contains the amount of the currency, including an implicit precision. Precision is always important for financial amounts. The currency element contains an ISO 4217 code for the currency.

Money is used in the following places: MonetaryComponent, Account, Claim, ClaimResponse, Contract, Coverage, CoverageEligibilityRequest, CoverageEligibilityResponse, ExplanationOfBenefit, InsurancePlan, Invoice, MedicationKnowledge, PaymentNotice and PaymentReconciliation

2.1.28.0.7.1 Alternate Representation

There are also circumstances where a financial amount must be represented as the numerator or denominator in a Ratio, where the type is currency. In this context, the Money amount is represented as a Quantity, using the MoneyQuantity constraint:

Profile Name	Rules	Formal Definitions
Money Quantity	id Level Location Description Expression mtqy-1 Rule (base) There SHALL be a code if there is a value and it SHALL be an expression of currency. If system is present, it SHALL be ISO 4217 (system = "urn:iso:std:iso:4217" - currency). (code.exists() or value.empty()) and (system.empty() or system = 'urn:iso:std:iso:4217')	XML, JSON
	Usage: (not used as yet)

Note that the profile is different from the other specializations because it is not a type, just rules applied where the Quantity type is used to represent Money amounts.

2.1.28.0.8 Range

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A set of ordered Quantity values defined by a low and high limit.

A Range specifies a set of possible values; usually, one value from the range applies (e.g. "give the patient between 2 and 4 tablets"). Ranges are typically used in instructions.

The unit and code/system elements of the low or high elements SHALL match. If the low or high elements are missing, the meaning is that the low or high boundaries are not known and therefore neither is the complete range.

The comparator flag on the low or high elements cannot be present. Note that the Range type should not be used to represent out of range measurements: A quantity type with the comparator element should be used instead.

The low and the high values are inclusive and are assumed to have arbitrarily high precision; e.g. the range 1.5 to 2.5 includes 1.50, and 2.50 but not 1.49 or 2.51.

Range is used in the following places: Dosage, UsageContext, Timing, ActivityDefinition, AllergyIntolerance, AuditEvent, BiologicallyDerivedProduct, ClinicalUseDefinition, Condition, Device, DeviceDefinition, DeviceRequest, Evidence, EvidenceReport, EvidenceVariable, FamilyMemberHistory, Goal, Group, InventoryItem, MeasureReport, MedicationKnowledge, MolecularSequence, Observation, ObservationDefinition, PlanDefinition, Procedure, RequestOrchestration, RiskAssessment, ServiceRequest, SpecimenDefinition, SubstanceReferenceInformation and SupplyRequest

2.1.28.0.9 Ratio

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A relationship between two Quantity values expressed as a numerator and a denominator.

The Ratio datatype should only be used to express a relationship of two numbers if the relationship cannot be suitably expressed using a Quantity and a common unit. Where the denominator value is known to be fixed to "1", Quantity should be used instead of Ratio.

Examples where a Quantity is typically used are rates, densities, concentrations. Examples where a Ratio is used are: titers (e.g. 1:128); concentration ratios where the denominator is significant (e.g. 5mg/10mL); observed frequencies (e.g. 2 repetitions/8 hr), and where the numerator or denominator is an amount of a currency (no UCUM code for $ etc.).

Common factors in the numerator and denominator are not automatically cancelled out. Ratios are not simply "structured numbers" - for example, blood pressure measurements (e.g. "120/60") are not ratios.

A proper ratio has both a numerator and a denominator; however, these are not mandatory in order to allow an invalid ratio with an extension with further information.

Ratio is used in the following places: Dosage, AdministrableProductDefinition, AuditEvent, BiologicallyDerivedProduct, Goal, Ingredient, InventoryItem, Medication, MedicationAdministration, MedicationKnowledge, NutritionOrder, NutritionProduct, Observation, PlanDefinition, ServiceRequest, Substance and SubstanceDefinition

2.1.28.0.10 RatioRange

FHIR Infrastructure Work Group

Maturity Level: 3

Standards Status: Trial Use

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A range of ratios of two Quantity values expressed as a low numerator, a high numerator, and a denominator.

The RatioRange datatype should only be used to express a range of ratios if the relationship cannot be suitably expressed using a Range and a common unit. Where the denominator value is known to be fixed to "1", Range should be used instead of RatioRange.

Common factors in the numerator and denominator are not automatically cancelled out. Ratios are not simply "structured numbers" - for example, blood pressure measurements (e.g. "120/60") are not ratios.

A proper ratio range has one of the numerators and a denominator; however, these are not mandatory in order to allow an invalid ratio with an extension with further information.

RatioRange is used in the following places: Ingredient

2.1.28.0.11 Period

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A time period defined by a start and end date/time.

A period specifies a range of times. The context of use will specify whether the entire range applies (e.g. "the patient was an inpatient of the hospital for this time range") or one value from the period applies (e.g. "give to the patient between 2 and 4 pm on 24-Jun 2013").

If the start element is missing, the start of the period is not known. If the end element is missing, it means that the period is ongoing. Alternatively, this may be represented by having an explicit end in the future, in which case this means the period is expected/planned to end at the specified time.

The end value includes any matching date/time. For example, the period 2011-05-23 to 2011-05-27 includes all the times from the start of the 23rd May through to the end of the 27th of May.

Period is used in the following places: Address, DataRequirement, HumanName, ContactPoint, MarketingStatus, Identifier, Availability, Timing, ExtendedContactDetail, Account, ActivityDefinition, AdverseEvent, AllergyIntolerance, Appointment, AuditEvent, BiologicallyDerivedProduct, CarePlan, CareTeam, ChargeItem, ChargeItemDefinition, Citation, Claim, ClaimResponse, ClinicalImpression, CodeSystem, CommunicationRequest, Composition, ConceptMap, Condition, Consent, Contract, Coverage, CoverageEligibilityRequest, CoverageEligibilityResponse, DetectedIssue, DeviceAssociation, DeviceDefinition, DeviceRequest, DeviceUsage, DiagnosticReport, DocumentReference, Encounter, EncounterHistory, Endpoint, EpisodeOfCare, EventDefinition, EvidenceReport, EvidenceVariable, ExplanationOfBenefit, FamilyMemberHistory, Flag, Group, InsurancePlan, InventoryReport, Invoice, Library, Measure, MeasureReport, MedicationAdministration, MedicationKnowledge, MedicationRequest, MedicationStatement, MedicinalProductDefinition, MetadataResource, NamingSystem, NutritionIntake, Observation, ObservationDefinition, Organization, OrganizationAffiliation, Patient, PaymentReconciliation, Permission, PlanDefinition, Practitioner, PractitionerRole, Procedure, Provenance, Questionnaire, RegulatedAuthorization, RelatedPerson, RequestOrchestration, ResearchStudy, ResearchSubject, RiskAssessment, Schedule, ServiceRequest, Specimen, SpecimenDefinition, SubscriptionTopic, SupplyDelivery, SupplyRequest, Task, Transport and ValueSet

2.1.28.0.12 SampledData

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Trial Use

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A SampledData provides a concise way to handle the data produced by devices that sample a particular physical state at a high frequency. A typical use for this is for the output of an ECG or EKG device. The datatype includes a series of raw decimal values (which are mostly simple integers) or codes, along with adjustments for scale and factor. These are interpreted such that

original measured value[i] = SampledData.data[i] * SampledData.factor + SampledData.origin.value

SampledData supports multi-dimensional data, where there is more than one measurement for each time point. If there is more than one dimension, the different dimensions are interlaced - all the data points for a particular time are represented together.

Data points are separated by by a single space (Unicode character u20). Each data point is either a decimal value or a code. Three special codes are defined:

• E: error - no valid measurement available for this data point
• L: below detection point - the value was below the device's detection limit (lowerLimit, which must be provided if this code is used)
• U: above detection point - the value was above the device's detection limit (upperLimit, which must be provided if this code is used)

Other codes may be used. In this case, the meaning of the codes is specified by the codeMap property which references a ConceptMap that defines the codes used in the data, and maps the codes to properly defined concepts in a CodeSystem. Note that in this case, source system defined in the ConceptMap is not used in the SampledData and is ignored. There SHALL only be one group in the ConceptMap. The ConceptMap cannot define meanings for any numerical values, nor for the codes 'E', 'U', or 'L' (nor, for safety, 'e', 'u', or 'l'), since they always have the meaning as defined above. There is no escape sequences; codes cannot contain spaces. Also, to make parsing simpler, codes cannot start with numerals.

SampledData is used in the following places: Observation

2.1.28.0.13 Identifier

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A string, typically numeric or alphanumeric, that is associated with a single object or entity within a given system. Typically, identifiers are used to connect content in resources to external content available in other frameworks or protocols. Identifiers are associated with objects and may be changed or retired due to human or system process and errors.

The system is an absolute URI that defines a set of identifiers (i.e. how the value is made unique). It might be a specific application or a recognized standard/specification for a set of identifiers or a way of making identifiers unique. FHIR defines some useful or important system URIs directly. Here are some example identifier namespaces:

• http://hl7.org/fhir/sid/us-ssn for United States Social Security Number (SSN) values
• http://ns.electronichealth.net.au/id/hi/ihi/1.0 for Australian Individual Healthcare Identifier (IHI) numbers
• urn:ietf:rfc:3986 for when the value of the identifier is itself a globally unique URI

If the system is a URL, it SHOULD resolve. Resolution might be to a web page that describes the identifier system and/or supports look-up of identifiers. Alternatively, it could be to a NamingSystem resource instance. Resolvable URLs are generally preferred by implementers over non-resolvable URNs, particularly opaque URNs such as OIDs (urn:oid:) or UUIDs (urn:uuid:). If used, OIDs and UUIDs may be registered in the HL7 OID registry and SHOULD be registered if the content is shared or exchanged across institutional boundaries.

It is up to the implementer organization to determine an appropriate URL or URN structure that will avoid collisions and to manage that space (and the resolvability of URLs) over time.

Note that the scope of a given identifier system may extend beyond identifiers that might be captured by a single resource. For example, some systems might draw all "order" identifiers from a single namespace, though some might be used on MedicationRequest while others would appear on ServiceRequest.

The value SHALL be unique within the defined system and have a consistent meaning wherever it appears. Identifier.system is always case sensitive. 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.

If the identifier value itself is naturally a globally unique URI (e.g. an OID, a UUID, or a URI with no trailing local part), then the system SHALL be "urn:ietf:rfc:3986", and the URI is in the value (OIDs and UUIDs using urn:oid: and urn:uuid: - see note on the V3 mapping and the examples). Naturally globally unique identifiers are those for which no other system has been assigned and where the value of the identifier is reasonably expected to not be re-used. Typically, these are absolute URIs of some kind.

In some cases, the system might not be known - only the value is known (e.g. a simple device that scans a barcode), or the system is known implicitly (simple exchange in a limited context, often driven by barcode readers). In this case, no useful matching may be performed using the value unless the system can be safely inferred by the context. Applications should provide a system wherever possible, as information sharing in a wider context is very likely to arise eventually, and values without a system are inherently limited in use. Whether or not the proper Identifier.system is known, the human-readable label for the Identifier.value typically appears in Identifier.type.text. E.g. 'BC provincial health number'.

In addition to the system (which provides a uniqueness scope) and the value, identifiers may also have a type, which may be useful when a system encounters identifiers with unknown system values. Note, however, that the type of an identifier is not a well-controlled vocabulary with wide variations in practice. The type deals only with general categories of identifiers and SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to variations in common usage.

The assigner is used to indicate what registry/state/facility/etc. assigned the identifier. As a Reference, the assigner can include just a text description in the display.

Identifier is used in the following places: Reference, Account, ActivityDefinition, ActorDefinition, AdministrableProductDefinition, AdverseEvent, AllergyIntolerance, Appointment, AppointmentResponse, ArtifactAssessment, Basic, BiologicallyDerivedProduct, BiologicallyDerivedProductDispense, BodyStructure, Bundle, CanonicalResource, CapabilityStatement, CarePlan, CareTeam, ChargeItem, ChargeItemDefinition, Citation, Claim, ClaimResponse, ClinicalImpression, ClinicalUseDefinition, CodeSystem, Communication, CommunicationRequest, Composition, ConceptMap, Condition, ConditionDefinition, Consent, Contract, Coverage, CoverageEligibilityRequest, CoverageEligibilityResponse, DetectedIssue, Device, DeviceAssociation, DeviceDefinition, DeviceDispense, DeviceMetric, DeviceRequest, DeviceUsage, DiagnosticReport, DocumentReference, Encounter, EncounterHistory, Endpoint, EnrollmentRequest, EnrollmentResponse, EpisodeOfCare, EventDefinition, Evidence, EvidenceReport, EvidenceVariable, ExampleScenario, ExplanationOfBenefit, FamilyMemberHistory, Flag, FormularyItem, GenomicStudy, Goal, GraphDefinition, Group, GuidanceResponse, HealthcareService, ImagingSelection, ImagingStudy, Immunization, ImmunizationEvaluation, ImmunizationRecommendation, ImplementationGuide, Ingredient, InsurancePlan, InventoryItem, InventoryReport, Invoice, Library, List, Location, ManufacturedItemDefinition, Measure, MeasureReport, Medication, MedicationAdministration, MedicationDispense, MedicationKnowledge, MedicationRequest, MedicationStatement, MedicinalProductDefinition, MessageDefinition, MessageHeader, MolecularSequence, NamingSystem, NutritionIntake, NutritionOrder, NutritionProduct, Observation, ObservationDefinition, OperationDefinition, Organization, OrganizationAffiliation, PackagedProductDefinition, Patient, PaymentNotice, PaymentReconciliation, Person, PlanDefinition, Practitioner, PractitionerRole, Procedure, Questionnaire, QuestionnaireResponse, RegulatedAuthorization, RelatedPerson, RequestOrchestration, Requirements, ResearchStudy, ResearchSubject, RiskAssessment, Schedule, SearchParameter, ServiceRequest, Slot, Specimen, SpecimenDefinition, StructureDefinition, StructureMap, Subscription, SubscriptionTopic, Substance, SubstanceDefinition, SubstanceNucleicAcid, SubstancePolymer, SubstanceProtein, SubstanceReferenceInformation, SubstanceSourceMaterial, SupplyDelivery, SupplyRequest, Task, TerminologyCapabilities, TestPlan, TestReport, TestScript, Transport, ValueSet and VisionPrescription

2.1.28.0.14 HumanName

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A name of a human with text, parts and usage information.

Names may be changed or repudiated. People may have different names in different contexts. Names may be divided into parts of different type that have variable significance depending on context, though the division into parts is not always significant. With personal names, the different parts might or might not be imbued with some implicit meaning; various cultures associate different importance with the name parts and the degree to which systems SHALL care about name parts around the world varies widely.

This table summarizes where common parts of a person's name are found.

Name	Example	Destination / Comments
Surname	Smith	Family Name
First name	John	Given Name
Title	Mr.	Prefix
Middle Name	Samuel	Subsequent Given Names
Patronymic	bin Osman	Family Name
Multiple family names	Carreño Quiñones	Family Name. See note below about decomposition of family name
Initials	Q.	Given Name as initial ("." recommended)
Nick Name	Jock	Given name, with Use = nickname
Qualifications	PhD	Suffix
Honorifics	Senior	Suffix
Voorvoegsel / Nobility	van Beethoven	Family Name. See note below about decomposition of family name

For further information, including all W3C International Examples , consult the examples. Note: Implementers should read the name examples for a full understanding of how name works.

The multiple given parts and family name combine to form a single name. Where a person has alternate names that may be used in place of each other (e.g. Nicknames, Aliases), these are different instances of HumanName.

The text element specifies the entire name as it should be displayed e.g. in an application UI. This may be provided instead of or as well as the specific parts. Applications updating a name SHALL ensure that when both text and parts are present, no content is included in the text that isn't found in a part. The correct order of assembly of the parts is culture dependent: the order of the parts within a given part type has significance and SHALL be observed. The appropriate order between family name and given names depends on culture and context of use. Note that there is an extension for the few times name assembly order is not fixed by the culture.

The given name parts may contain whitespace, though generally they don't. Initials may be used in place of the full name if that is all that is recorded. Systems that operate across cultures should generally rely on the text form for presentation and use the parts for index/search functionality. For this reason, applications SHOULD populate the text element for future robustness.

In some cultures (e.g. German, Dutch, Spanish, Portuguese), family names are complex and composed of various parts that may need to be managed separately, e.g. they have differing significance for searching. In these cases, the full family name is populated in family, and a decomposition of the name can be provided using the family extensions own-name, own-prefix, partner-name, partner-prefix, fathers-family and mothers-family.

For robust search, servers should search the parts of a family name independently. E.g. Searching either Carreno or Quinones should match a family name of "Carreno Quinones". HL7 affiliates, and others producing implementation guides, may make more specific recommendations about how search should work in specific cultures or environments.

HumanName is used in the following places: ExtendedContactDetail, Patient, Person, Practitioner and RelatedPerson

2.1.28.0.15 Address

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

An address expressed using postal conventions (as opposed to GPS or other location definition formats). This datatype may be used to convey addresses for use in delivering mail as well as for visiting locations which might not be valid for mail delivery. There are a variety of postal address formats defined around the world.

The text element specifies the entire address as it should be displayed e.g. on a postal label. This may be provided instead of or as well as the specific parts. Applications updating an address SHALL ensure that when both text and parts are present, no content is included in the text that isn't found in a part.

Address is used in the following places: ExtendedContactDetail, Claim, ClaimResponse, ExplanationOfBenefit, InventoryItem, Location, Patient, Person, Practitioner and RelatedPerson

2.1.28.0.16 ContactPoint

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

Details for all kinds of technology-mediated contact points for a person or organization, including telephone, email, etc.

If capturing a phone, fax or similar contact point, the value should be a properly formatted telephone number according to ITU-T E.123 . However, this is frequently not possible due to legacy data and/or clerical practices when recording contact details. For this reason, phone, fax, pager, and email addresses are not handled as formal URLs. For other kinds of contact points, the system is "other" and the value SHOULD be a URL so that its use can be determined automatically. Typical URL schemes used in the value are http{s}: for web addresses, and URL schemes for various kinds of messaging systems. If the value is not a URL, then human interpretation will be required.

ContactPoint is used in the following places: VirtualServiceDetail, ContactDetail, ExtendedContactDetail, CareTeam, Device, DeviceDefinition, Endpoint, MessageHeader, Patient, Person, Practitioner, RelatedPerson and Subscription

2.1.28.0.17 Timing

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

Describes the occurrence of an event that may occur multiple times. Timing schedules are used for specifying when events are expected or requested to occur and may also be used to represent the summary of a past or ongoing event. For simplicity, the definitions of Timing components are expressed as 'future' events, but such components can also be used to describe historic or ongoing events.

A Timing schedule can be a list of events and/or criteria for when the event happens, which can be expressed in a structured form and/or as a code. When both event and a repeating specification are provided, the list of events should be understood as an interpretation of the information in the repeat structure.

Note: The Timing datatype allows modifier extensions.

If the timing schedule has repeating criteria, the repeat can occur a given number of times per the specified duration or in relation to some repeating real-world event. If no end condition is specified, the schedule will terminate on some criteria that are expressed elsewhere.

Many systems avoid the complexity of the Timing structure by using a text field for timing instructions. This maps to Timing.code.text. For example, the text instruction "take medication in the morning on weekends and days off work' would be represented as:

  "timing": {
    "code" : {
      "text" : "Take medication in the morning on weekends and days off work"
    }
  }

Note, though, that some systems include timing details in something like 'Dosage instructions' which is wider than just Timing; those systems do not use the Timing datatype. Other systems use a set of 'common' codes - including, but usually not limited to, widely understood acronyms such as "BID". If a Timing.code is provided, the code is understood to be a complete statement of whatever is specified in the structured timing data (except for Timing.repeat.bounds, which applies to the code), and either the code or the data may be used to interpret the Timing. A structured timing specification SHOULD be provided whenever possible, unless the code is BID, TID, QID, AM or PM, which have a ubiquitous meaning.

This table summarizes some common uses of the Timing Datatype criteria.

description

duration

durationUnit

frequency

frequencyMax

period

periodUnit

periodMax

Day of Week

Time Of Day

when

offset

bounds[x]

count

Every 8 hours

1

8

h

Every 7 days

1

7

d

3 times a day

3

1

d

3-4 times a day

3

4

1

d

Every 4-6 hours

1

4

h

6

Every 21 days for 1 hour

1

hr

1

21

d

Three times a week for ½ hour

0.5

hr

3

1

wk

With breakfast

CM

For 5 minutes, 10 minutes before meals

5

min

AC

10

1 tablet 3 times daily, 30 minutes before meals

3

1

d

AC

30

BID, 30 mins before meal, for next 10 days

2

1

d

AC

30

Duration = 10 days

TID, for 14 days

3

1

d

Duration = 14 days

BID, start on 7/1/2015 at 1:00 PM

2

1

d

Period.start = 2015-07-01T13:00:00

Mon, Wed, Fri Morning

1

1

d

mon | wed | fri

MORN

Every day at 10am

1

1

d

10:00

Take once, at any time

1

Take every second day, in the morning, until 20 have been taken

1

2

d

MORN

20

This table shows the relationship between the codes provided as part of the base specification, and the structured data portions of the Timing type:

description	duration	durationUnit	frequency	frequencyMax	period	periodUnit	periodMax	when	bounds[x]
QOD			1		2	d
QD			1		1	d
BID			2		1	d
TID			3		1	d
QID			4		1	d
Q4H			1		4	h
Q6H			1		6	h
AM			1		1	d		MORN
PM			1		1	d		AFT or EVE

These codes SHALL be understood as having the formal meanings documented in this table. Note that BID, etc. are defined as 'at institutionally specified times'. For example, an institution may choose that BID is "always at 7am and 6pm". If it is inappropriate for this choice to be made, the code BID should not be used. Instead, a distinct organization-specific code should be used in place of the HL7-defined BID code and/or a structured representation should be used (in this case, timeOfDay).

Timing is used in the following places: Dosage, TriggerDefinition, ActivityDefinition, AdverseEvent, CareTeam, ChargeItem, Contract, DeviceRequest, DeviceUsage, MedicationAdministration, MedicationStatement, NutritionIntake, NutritionOrder, Observation, PlanDefinition, Procedure, RequestOrchestration, ServiceRequest, SupplyDelivery, SupplyRequest and VerificationResult

2.1.28.0.18 Signature

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Trial Use

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

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 digital-signature process.

Notes:

• The Signature datatype can be used to hold a digital-signature, but may also be used to hold electronic-signatures.
• Electronic-Signatures, such as image of ink signature, do not protect the signed content from change, but do carry details about who signed, when signature happened, and what the signature means.
• One consequence of digital-signature on a Resource (document) is that URLs, identifiers and internal references are frozen and cannot be changed. This might be a desired feature, but it may also cripple interoperability between closed ecosystems where re-identification frequently occurs. For this reason, it is recommended that systems consider carefully the impact of any signature processes. The impact of signatures on Document bundles and their related processes is the most well understood use of digital signatures.
• Note that following common normalization procedures in XML can assign the same normalized text to resources with slightly different meanings, since leading whitespace matters in markdown text, and the XML representation serializes the markdown datatype using attributes.

 

2.1.28.0.18.1 XML Signature rules

When the signature is an XML Digital Signature (contentType = application/signature+xml), the following rules apply:

• The Signature.data is base64 encoded XML-Signature
• The XML-Signature is a Detached Signature (where the content that is signed is separate from the signature itself)
• The Signature SHOULD conform to XAdES-X-L for support of Long Term signatures . The XAdES-X-L specification adds the timestamp of the signing, inclusion of the signing certificate, and statement of revocation
• When FHIR Resources are signed, the signature is across the Canonical XML form of the resource(s)
• The Signature SHOULD use the hashing algorithm SHA-256. Signature validation policy will apply to the signature and determine acceptability
• The Signature SHALL include a "CommitmentTypeIndication" element for the Purpose(s) of Signature. The Purpose can be the action being attested to, or the role associated with the signature. The value shall come from ASTM E1762-95(2013). The Signature.type shall contain the same values as the CommitmentTypeIndication element.

There are three levels of signature verification:

1. Verifying that the Digital Signature block itself has integrity through verifying the signature across the XML-Signature.
2. Confirming that the signer was authentic, not revoked, and appropriate to the signature purpose.
3. Confirming that the signed content of interest is unmodified using the hash algorithm.

Deviations from these guidelines would need to be expressed in site policy and would be enumerated in the XML-Signature block. For example, some environments may choose a different XAdES profile, hashing algorithm, policy identifier, or signature purpose vocabulary.

2.1.28.0.18.2 JSON Signature rules

When the signature is an JSON Digital Signature (contentType = application/jose), the following rules apply:

• The Signature.data is base64 encoded JWS-Signature RFC 7515: JSON Web Signature (JWS)
• The signature is a Detached Signature (where the content that is signed is separate from the signature itself)
• When FHIR Resources are signed, the signature is across the Canonical JSON form of the resource(s)
• The Signature SHOULD use the hashing algorithm SHA-256. Signature validation policy will apply to the signature and determine acceptability
• The Signature SHALL include a "srCms signer commitments" element for the Purpose(s) of Signature. The Purpose can be the action being attested to, or the role associated with the signature. The value shall come from ASTM E1762-95(2013). The Signature.type shall contain the same values as the srCms element.
• The Signature SHOULD conform to JAdES-XL for support of long term signatures. The JAdES-X-L specification adds the timestamp of the signing, inclusion of the signing certificate, and statement of revocation

There are three levels of signature verification:

1. Verifying that the Digital Signature block itself has integrity through verifying the signature across the JWS-Signature.
2. Confirming that the signer was authentic, not revoked, and appropriate to the signature purpose.
3. Confirming that the signed content of interest is unmodified using the hash algorithm.

Deviations from these guidelines would need to be expressed in site policy and would be enumerated in the JWS-Signature block. For example, some environments may choose a different hashing algorithm, policy identifier, or signature purpose vocabulary.

Signature is used in the following places: Bundle, Contract, Provenance and VerificationResult

2.1.28.0.19 Annotation

FHIR Infrastructure Work Group

Maturity Level: 5

Standards Status: Normative

See also Examples, Detailed Descriptions, Mappings, Profiles, Extensions and R4 Conversions

A text note which also contains information about who made the statement and when.

Notes:

• Systems that do not have structured annotations communicate a single annotation with no author or time.
• Annotations SHOULD NOT be used to communicate "modifying" information that could be computable (this is a SHOULD because enforcing user behavior is nearly impossible).
• For communicating the author as a string value, implementers SHOULD use use Annotation.authorReference.display instead of the the anti-pattern Annotation.authorString (authorString cannot be removed because this datatype is Normative).
• This element may need to be included in the Resource human-readable narrative because of the potential for modifying information.

Annotation is used in the following places: AdverseEvent, AllergyIntolerance, Appointment, BiologicallyDerivedProductDispense, CarePlan, CareTeam, ChargeItem, Citation, ClinicalImpression, Communication, CommunicationRequest, Composition, Condition, Contract, DetectedIssue, Device, DeviceDefinition, DeviceDispense, DeviceRequest, DeviceUsage, DiagnosticReport, Evidence, EvidenceReport, EvidenceVariable, FamilyMemberHistory, GenomicStudy, Goal, GuidanceResponse, ImagingStudy, Immunization, InventoryItem, InventoryReport, Invoice, List, MedicationAdministration, MedicationDispense, MedicationKnowledge, MedicationRequest, MedicationStatement, NutritionIntake, NutritionOrder, NutritionProduct, Observation, Procedure, RequestOrchestration, ResearchStudy, RiskAssessment, ServiceRequest, Specimen, SubstanceDefinition, Task, Transport and VisionPrescription

2.1.28.0.20 Open Type Element

Some elements do not have a specified type. The type is represented by the wildcard symbol "*". In these cases, the element type may be one of the following:

Primitive Types

• base64Binary
• boolean
• canonical
• code
• date
• dateTime
• decimal
• id
• instant
• integer
• integer64
• markdown
• oid
• positiveInt
• string
• time
• unsignedInt
• uri
• url
• uuid

Datatypes

• Address
• Age
• Annotation
• Attachment
• CodeableConcept
• CodeableReference
• Coding
• ContactPoint
• Count
• Distance
• Duration
• HumanName
• Identifier
• Money
• Period
• Quantity
• Range
• Ratio
• RatioRange
• Reference
• SampledData
• Signature
• Timing

MetaDataTypes

• ContactDetail
• DataRequirement
• Expression
• ParameterDefinition
• RelatedArtifact
• TriggerDefinition
• UsageContext
• Availability
• ExtendedContactDetail

Special Types

• Dosage
• Meta

The element name ends with "[x]", and this is replaced with the Title cased name of the datatype.

Open types are used in the following places: ElementDefinition, Parameters, Task and Transport

2.1.28.0.21 Other Types

The following types are defined as part of the datatypes, but are documented elsewhere in the specification:

• Resource - the conceptual base class for all resources
• Reference - for references from one resource to another
• Extension - used to convey additional data in a resource
• Narrative - conveys a human-readable representation of the content of a resource