This page is part of the FHIR Specification (v1.4.0: STU 3 Ballot 3). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions . Page versions: R5 R4B R4 R3 R2

• Data Types
• Examples
• Detailed Descriptions
• Mappings

1.18.0 Data Types

FHIR Infrastructure Work Group

Maturity Level: 3

Ballot Status: DSTU 2

The FHIR specification defines a set of data types that are used for the resource elements. There are two categories of data types: simple / primitive types, which are single elements, and complex types, which are re-usable clusters of elements. This page describes the data types. See also the Examples, Detailed Descriptions and Mappings.

Table of Contents

Primitive Types

Complex Types

White = abstract type. Light blue - types. Light Pink - Profile on Type. The data types are also available as a W3C Schema.

1.18.0.1 Primitive Types

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

Primitive Types
FHIR Name	Value Domain	XML Representation	JSON representation
boolean	true | false	xs:boolean, except that 0 and 1 are not valid values	JSON boolean (true or false)
integer	A signed 32-bit integer (for larger values, use decimal)	xs:int, except that leading 0 digits are not allowed	JSON number (with no decimal point)
string	A sequence of Unicode characters	xs:string	JSON String
	Note that strings SHALL NOT exceed 1MB in size. String should not contain Unicode character points below 32, except for u0009 (horizontal tab), u0010 (carriage return) and u0013 (line feed)
	Todo: is there any reason not to make this a SHALL?
decimal	Rational numbers that have a decimal representation. See below about the precision of the number	xs:decimal, except that decimals may not use exponents, and leading 0 digits are not allowed	A JSON number, except that exponents are not allowed
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
	URIs can be absolute or relative, and may have an optional fragment identifier
base64Binary	A stream of bytes, base64 encoded (RFC 4648 )	xs:base64Binary	A JSON string - base64 content
	Todo: is it possible to impose an upper absolute limit on a base64Binary (for denial of service reasons, like on string)?
instant	An instant in time - known at least to the second and always includes a time zone. Note: This is intended for precisely observed times (typically system logs etc.), and not human-reported times - for them, use date and dateTime. 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).
date	A date, or partial date (e.g. just year or year + month) as used in human communication. There is no time zone. 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]{4}(-(0[1-9]|1[0-2])(-(0[0-9]|[1-2][0-9]|3[0-1]))?)?
dateTime	A date, date-time or partial date (e.g. just year or year + month) as used in human communication. If hours and minutes are specified, a time zone SHALL be populated. Seconds must be provided due to schema type constraints but may be zero-filled and may be ignored. Dates SHALL be valid dates. The time "24:00" is not allowed	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]{4}(-(0[1-9]|1[0-2])(-(0[0-9]|[1-2][0-9]|3[0-1])(T([01][0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9](\.[0-9]+)?(Z|(\+|-)((0[0-9]|1[0-3]):[0-5][0-9]|14:00)))?)?)?
time	A time during the day, with no date specified (can be converted to a Duration since midnight). Seconds must be provided due to schema type constraints but may be zero-filled and may be ignored. The time "24:00" is not allowed, and neither is a time zone	xs:time	A JSON string - an xs:time
	Regex: ([01][0-9]|2[0-3]):[0-5][0-9]:[0-5][0-9](\.[0-9]+)?

Notes:

• For all the types, the XML and JSON representations are the same except for different escaping in XML and JSON
• Boolean values can also be represented using coded values (such as HL7 v2 Table 0136). See Observation for one such use
• The regexes may allow a broader set of values than are actually valid (e.g. leap years) so additional validation is needed
• The precision of the decimal value has signficance:
  • 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 there is no absolute limit to the magnitude of the value, though large and/or highly precise values are extremely rare in medicine. One element where highly precise decimals may be encountered is the Location coordinates

1.18.0.1.1 XML and JSON representations

All elements using these primitive types have some combination of value as described above, an internal identity (e.g. xml:id), and extensions. The value is represented in XML as an attribute named "value":

  <count value="2"/>

and as the value of the property in JSON:

  "count" : 2

For additional details, including how the internal identity and extensions are represented, see the XML and JSON formats. When the value is missing, it is not represented in the instance; the XML value attribute or the JSON property are 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, whitespace in string values is always significant. Primitive types other than string SHALL NOT have leading or trailing whitespace.

1.18.0.1.2 Simple Restrictions

In addition to the base primitive types, a few additional primitive types are defined as restrictions on one of the other primitive types.

FHIR Name	Base FHIR Type	Description
code	string	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 regex: [^\s]+([\s]?[^\s]+)*
oid	uri	An OID represented as a URI (RFC 3001 ); e.g. urn:oid:1.2.3.4.5 regex: urn:oid:[0-2](\.[1-9]\d*)+
id	string	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.) regex: [A-Za-z0-9\-\.]{1,64}
markdown	string	A string that may contain markdown syntax for optional processing by a markdown presentation engine
unsignedInt	int	Any non-negative integer (e.g. >= 0) regex: [0-9]+
positiveInt	int	Any positive integer (e.g. > 0) regex: [1-9][0-9]*

Some additional notes 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)

Some additional notes about the markdown datatype:

• Systems are not required to have markdown support, and there is considerable variation in markdown syntax, so the content of a string should be readable without markdown processing, per markdown philosophy
• The preferred markdown syntax is described at http://daringfireball.net/projects/markdown/syntax (see tests here: http://daringfireball.net/projects/downloads/MarkdownTest_1.0.zip )
• Markdown content should not contain Unicode character points below 32, except for u0009 (horizontal tab), u0010 (carriage return) and u0013 (line feed). Todo: is there any reason not to make this a SHALL?

DSTU Note: CommonMark is a new arrival but may gain sufficient impetus to be preferred in a future version.

Feedback is welcome here .

---

1.18.0.2 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 data type 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 data types 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 Data types

1.18.0.3 Attachment

See also Examples, Detailed Descriptions and Mappings.

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.

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: BodySite, Communication, CommunicationRequest, Contract, DiagnosticReport, DocumentManifest, DocumentReference, GuidanceResponse, HealthcareService, ImagingStudy, Library, Media, ModuleDefinition, Observation, Patient, Person, Practitioner, Questionnaire, QuestionnaireResponse and RelatedPerson

1.18.0.4 Coding

See also Examples, Detailed Descriptions and Mappings.

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.

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 adds no other value.

The system is a URI that references 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. The system URI SHALL NOT contain a reference to a value set (e.g. ValueSet.url). If the code is taken from a CodeSystem resource, CodeSystem.url is the correct value for the system uri.

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.

Where the code system defines multiple possible display strings, one of these SHALL be used in display. If one is labeled as preferred, it SHOULD be used. If the code system does not define a text representation (e.g. SNOMED CT Expressions) then display 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 may 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 code.

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: CodeableConcept, Signature, Account, AuditEvent, Claim, ClaimResponse, CodeSystem, Conformance, Contract, Coverage, DocumentReference, EligibilityRequest, EligibilityResponse, EnrollmentRequest, EnrollmentResponse, ExpansionProfile, ExplanationOfBenefit, GuidanceResponse, ImagingStudy, MessageHeader, PaymentNotice, PaymentReconciliation, ProcessRequest, ProcessResponse, Provenance, Questionnaire, QuestionnaireResponse, StructureDefinition, Subscription, Task, TestScript, ValueSet and VisionPrescription

Design 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 data type 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 data type 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.

1.18.0.5 CodeableConcept

See also Examples, Detailed Descriptions and Mappings.

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.

Each coding is a representation of the concept as described above. 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). The different codings 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.

Whether or not coding elements are present, 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 of the codings may be flagged as the userSelected - the code or concept that the user actually selected directly. When none of the coding elements is marked as userSelected, the text (if present) is the preferred source of meaning.

CodeableConcept is used in the following places: Identifier, Account, AllergyIntolerance, Appointment, AppointmentResponse, AuditEvent, Basic, BodySite, CarePlan, CareTeam, ClinicalImpression, CodeSystem, Communication, CommunicationRequest, Composition, ConceptMap, Condition, Conformance, Contract, DataElement, DetectedIssue, Device, DeviceComponent, DeviceMetric, DeviceUseRequest, DeviceUseStatement, DiagnosticOrder, DiagnosticReport, DocumentManifest, DocumentReference, Encounter, EpisodeOfCare, FamilyMemberHistory, Flag, Goal, Group, GuidanceResponse, HealthcareService, ImagingExcerpt, ImagingObjectSelection, Immunization, ImmunizationRecommendation, ImplementationGuide, List, Location, Media, Medication, MedicationAdministration, MedicationDispense, MedicationOrder, MedicationStatement, MessageHeader, ModuleDefinition, NamingSystem, NutritionOrder, Observation, OperationDefinition, OperationOutcome, Order, Organization, Patient, Practitioner, PractitionerRole, Procedure, ProcedureRequest, Protocol, Provenance, Questionnaire, ReferralRequest, RelatedPerson, RiskAssessment, Schedule, SearchParameter, Sequence, Slot, Specimen, StructureDefinition, StructureMap, Substance, SupplyDelivery, SupplyRequest, Task, TestScript, ValueSet and VisionPrescription

1.18.0.6 Quantity

See also Examples, Detailed Descriptions and Mappings.

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

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 is able to 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 actually 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: Ratio, Group, Observation, Questionnaire, QuestionnaireResponse and Sequence

1.18.0.6.1 Defined Variations on Quantity

These are used as types in resource content models, but they are really just a Quantity with some rules:

Age	A duration (length of time) with a UCUM code	StructureDefinition (XML, JSON)	Condition and FamilyMemberHistory
Count	A count of a discrete element (no unit)	StructureDefinition (XML, JSON)	(not used as yet)
Money	An amount of money. With regard to precision, see [Decimal Precision](datatypes.html#precision)	StructureDefinition (XML, JSON)	Account, Claim, ClaimResponse, Contract, EligibilityResponse, ExplanationOfBenefit and PaymentReconciliation
Distance	A measure of distance	StructureDefinition (XML, JSON)	(not used as yet)
Duration	A length of time	StructureDefinition (XML, JSON)	Encounter, Goal, GuidanceResponse, MedicationOrder and Protocol
SimpleQuantity	A fixed quantity (no comparator)	StructureDefinition (XML, JSON)	Range, SampledData, CarePlan, Claim, Contract, ExplanationOfBenefit, Immunization, Medication, MedicationAdministration, MedicationDispense, MedicationOrder, MedicationStatement, NutritionOrder, Observation, Protocol, Specimen, Substance, SupplyDelivery and VisionPrescription

1.18.0.7 Range

See also Examples, Detailed Descriptions and Mappings.

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: Condition, FamilyMemberHistory, Group, GuidanceResponse, MedicationAdministration, MedicationDispense, MedicationOrder, MedicationStatement, Observation, Protocol and RiskAssessment

1.18.0.8 Ratio

See also Examples, Detailed Descriptions and Mappings.

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

Common factors in the numerator and denominator are not automatically cancelled out. The Ratio data type is used for titers (e.g. "1:128") and other quantities produced by laboratories that truly represent ratios. Ratios are not simply "structured numbers" - for example blood pressure measurements (e.g. "120/60") are not ratios. In addition, ratios are used where common factors in the numerator and denominator do not cancel out. The most common example of this is where the ratio represents a unit cost, and the numerator is a currency (e.g. 50/$10).

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: Medication, MedicationAdministration, MedicationDispense, MedicationOrder, MedicationStatement, NutritionOrder, Observation and Substance

1.18.0.9 Period

See also Examples, Detailed Descriptions and Mappings.

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, or the start may be in the past, and the end date in the future, which means that 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: Identifier, Account, CarePlan, CareTeam, Claim, CommunicationRequest, Composition, Condition, Contract, Coverage, DeviceUseRequest, DeviceUseStatement, DiagnosticReport, DocumentReference, EligibilityRequest, Encounter, EpisodeOfCare, ExplanationOfBenefit, FamilyMemberHistory, Flag, Group, HealthcareService, MeasureReport, MedicationAdministration, MedicationOrder, MedicationStatement, ModuleDefinition, NamingSystem, Observation, Patient, PaymentReconciliation, Practitioner, PractitionerRole, Procedure, ProcedureRequest, ProcessRequest, Provenance, ReferralRequest, RelatedPerson, RiskAssessment, Schedule, Specimen and SupplyDelivery

1.18.0.10 SampledData

See also Examples, Detailed Descriptions and Mappings.

Data that comes from a series of measurements taken by a device, with upper and lower limits. There may be more than one dimension in the data.

A SampledData provides a concise way to handle the data produced by devices that sample a physical particular state at a high frequency. A typical use for this is for the output of an ECG or EKG device.

The digits are a set of decimal values separated by a single space (Unicode character u20). In addition to decimal values, the special values "E" (error), "L" (below detection limit) and "U" (above detection limit) can also be used. If there is more than one dimension, the different dimensions are interlaced - all the data points for a particular time are represented together. The default value for factor is 1.

SampledData is used in the following places: Observation

1.18.0.11 Identifier

See also Examples, Detailed Descriptions and Mappings.

A numeric or alphanumeric string 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 value SHALL be unique within the defined system and have a consistent meaning wherever it appears. Both system and value are always case sensitive.

The system referred to by means of a URI defines how the identifier is defined (i.e. how the value is made unique). It might be a specific application or a recognized standard/specification for a set or identifiers or a way of making identifiers unique. FHIR defines some useful or important URIs directly.

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 MedicationOrder while others would appear on ProcedureRequest or DiagnosticOrder.

If the identifier itself is naturally globally unique (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. In some cases, the system may 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. This practice should be avoided where possible, as information sharing in a wider context is very likely to arise eventually, and values without a system are inherently limited in use.

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.

Identifier is used in the following places: Account, AllergyIntolerance, Appointment, AppointmentResponse, AuditEvent, Basic, BodySite, CarePlan, CareTeam, Claim, ClaimResponse, CodeSystem, Communication, CommunicationRequest, Composition, ConceptMap, Condition, Contract, Coverage, DataElement, DetectedIssue, Device, DeviceComponent, DeviceMetric, DeviceUseRequest, DeviceUseStatement, DiagnosticOrder, DiagnosticReport, DocumentManifest, DocumentReference, EligibilityRequest, EligibilityResponse, Encounter, EnrollmentRequest, EnrollmentResponse, EpisodeOfCare, ExpansionProfile, ExplanationOfBenefit, FamilyMemberHistory, Flag, Goal, Group, GuidanceResponse, HealthcareService, ImagingStudy, Immunization, ImmunizationRecommendation, List, Location, Measure, MeasureReport, Media, MedicationAdministration, MedicationDispense, MedicationOrder, MedicationStatement, ModuleDefinition, NutritionOrder, Observation, Order, OrderResponse, Organization, Patient, PaymentNotice, PaymentReconciliation, Person, Practitioner, PractitionerRole, Procedure, ProcedureRequest, ProcessRequest, ProcessResponse, Protocol, Provenance, Questionnaire, QuestionnaireResponse, ReferralRequest, RelatedPerson, RiskAssessment, Schedule, Slot, Specimen, StructureDefinition, StructureMap, Substance, SupplyDelivery, SupplyRequest, Task, TestScript, ValueSet and VisionPrescription

1.18.0.12 HumanName

See also Examples, Detailed Descriptions and Mappings.

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 may or may 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 repeats
Initials	Q.	Given Name as initial ("." recommended)
Nick Name	Jock	Given name, with Use = common
Qualifications	PhD	Suffix
Honorifics	Senior	Suffix

For further information, including all W3C International Examples , consult the examples.

The multiple given and family name parts combine to form a single name. Multiple given and family names are for when a person's name has multiple given names (relatively common across cultures) and multiple surnames (less common). Where a person has alternate names that may be used in place of each other, these are different instances of HumanName.

The text element specifies the entire name as it should be represented. This may be provided instead of or as well as specific parts, and can be built from the parts, though the correct order of assembly 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.

The parts of a name SHOULD NOT contain whitespace. For family name, hyphenated names such as "Smith-Jones" are a single name, but names with spaces such as "Smith Jones" are broken into multiple parts. For given names, 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 reasons, applications SHOULD populate the text element for future robustness.

Applications updating a name SHALL ensure either that the text and the parts are in agreement, or that only one of the two is present. Systems that do not support as many name parts as are provided in an instance may wish to append some of the parts together using spaces

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

1.18.0.13 Address

See also Examples, Detailed Descriptions and Mappings.

An address expressed using postal conventions (as opposed to GPS or other location definition formats). This data type may be used to convey addresses for use in delivering mail as well as for visiting locations and 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 represented. This may be provided instead of or as well as the specific parts. Applications updating an address SHALL ensure either that the text and the parts are in agreement, or that only one of the two is present.

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

1.18.0.14 ContactPoint

See also Examples, Detailed Descriptions and Mappings.

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, page and email addresses are not handled as formal URLs. For other kinds of contacts, 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.

The rank element can be used to specify a preference for the order in which a set of contacts is used. Contacts are ranked with lower values coming before higher values. Note that rank does not necessarily follow the order in which the contacts are represented in the instance.

ContactPoint is used in the following places: CodeSystem, CompartmentDefinition, ConceptMap, Conformance, DataElement, Device, ExpansionProfile, HealthcareService, ImplementationGuide, Location, MessageHeader, NamingSystem, OperationDefinition, Organization, Patient, Person, Practitioner, PractitionerRole, Questionnaire, RelatedPerson, SearchParameter, StructureDefinition, StructureMap, Subscription, TestScript and ValueSet

1.18.0.15 Timing

See also Examples, Detailed Descriptions and Mappings.

Specifies an event that may occur multiple times. Timing schedules are not used for recording when things did happen, but when they are expected or requested to occur. A Timing schedule can be a list of events and/or criteria for when the event is to happen, 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.

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 real world event. If no end condition is specified, the schedule will terminate on some criteria that are expressed elsewhere.

This table summarises some common uses of the Timing Data Type criteria.

description	duration	durationUnit	frequency	frequencyMax	period	periodUnit	periodMax	when	offset	bounds[x]
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, low = 2015-07-01T13:00:00

Many systems avoid the complexity of the Timing structure by using a text field for these things (e.g. "Dosage Text"). Those systems do not use the Timing data type. Other systems use a set of 'common' codes - including, but usually not limited to, widely understood acronyms such as "BID". If a code is provided, the code is understood to be a complete statement of whatever is specified in the structured timing data, 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 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
PM			1		1	d

These codes SHALL be understood as having the formal meanings documented in this table.

Additional Notes:

• To Do: there's no way to indicate the time of day at which AM or PM occur. Add to events?
• 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 the a structured representation should be used (in this case, specifying the two event times).

Timing is used in the following places: CarePlan, DeviceMetric, DeviceUseRequest, DeviceUseStatement, MedicationDispense, MedicationOrder, MedicationStatement, NutritionOrder, Order, ProcedureRequest, Protocol and SupplyRequest

1.18.0.16 Signature

See also Examples, Detailed Descriptions and Mappings.

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 JWT), which is able to provide non-repudiation proof, or it may be a graphical image that represents a signature or a signature process.

Note: One consequence of signing the 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.

 

1.18.0.16.1 XML Signature rules

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

• The Signature.blob 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 accross the Canonical XML form of the resource(s)
• The Signature SHOULD use the hashing algorithm sha256. 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 committmentTypeIndication

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.

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

1.18.0.17 Annotation

See also Examples, Detailed Descriptions and Mappings.

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

Systems that do not have structured annotations simply communicate a single annotation with no author or time.

This element may need to be included in narrative because of the potential for modifying information.

Annotations SHOULD NOT be used to communicate "modifying" information that could be computable (this is a SHOULD because enforcing user behavior is nearly impossible).

Annotation is used in the following places: AllergyIntolerance, CarePlan, Device, DiagnosticOrder, FamilyMemberHistory, Goal, Immunization, List, MedicationAdministration, MedicationDispense, MedicationOrder, MedicationStatement, Procedure and ProcedureRequest

1.18.0.18 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:

• boolean
• integer
• decimal
• base64Binary
• instant
• string
• uri
• date
• dateTime
• time
• code
• oid
• id
• unsignedInt
• positiveInt
• markdown
• Annotation
• Attachment
• Identifier
• CodeableConcept
• Coding
• Quantity
• Range
• Period
• Ratio
• SampledData
• Signature
• HumanName
• Address
• ContactPoint
• Timing
• Reference - a reference to another resource
• Meta

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

Open references are used in the following places: Parameters and Task

1.18.0.19 Other Types

The following types are defined as part of the data types, 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