---
type: "resource-definitions"
title: "Group Definitions"
resource: "Group"
---

# Group Definitions

<a id="Group"></a>

## Group
Group of multiple entities

**Definition:** Represents a defined collection of entities that may be discussed or acted upon collectively but which are not typically expected to act collectively.  These collections are also not typically formally or legally recognized.

NOTE: Group may be used to define families or households, which in some circumstances may act collectively or have a degree of legal or formal recognition.  This should be considered an exception.  When Group is used for types of entities other than Patient or RelatedPerson, the expectation remains that the Group will not act collectively or have formal recognition - use Organization if these behaviors are needed.

For example, it is possible for a 'family' Group to be a performer of an Observation or owner of a Task.  However, this is not permitted for a Group made up of Practitioners, PractitionerRoles or Organizations.  Organization or CareTeam would need to be used instead.  A Group of Practitioners could, however, be a subject of an Observation.

**Comments:** If both Group.characteristic and Group.member are present, then the members are the individuals who were found who met the characteristic.  It's possible that there might be other candidate members who meet the characteristic and aren't (yet) in the list.  All members SHALL have the listed characteristics.

**Cardinality:** 0..*

**Constraints:** grp-2 | error | Group.type SHALL be defined if Group.membership is either 'definitional' or 'enumerated' | type.exists() or (membership = 'conceptual')

**Mappings:** rim=Entity[determinerCode="GRP" or determinerCode="GRP_KIND"]; interface=Participant; w5=administrative.group


<a id="Group.url"></a>

## Group.url
Canonical identifier for this Group, represented as an absolute URI (globally unique)

**Definition:** An absolute URI that is used to identify this Group when it is referenced in a specification, model, design or an instance; also called its canonical identifier. This SHOULD be globally unique and SHOULD be a literal address at which an authoritative instance of this Group is (or will be) published. This URL can be the target of a canonical reference. It SHALL remain the same when the Group is stored on different servers.

**Comments:** Can be a urn:uuid: or a urn:oid: but real http: addresses are preferred.  Multiple instances may share the same URL if they have a distinct version.

The determination of when to create a new version of a resource (same url, new version) vs. defining a new artifact is up to the author.  Considerations for making this decision are found in [Technical and Business Versions](resource.html#versions).

In some cases, the resource can no longer be found at the stated url, but the url itself cannot change. Implementations can use the [meta.source](resource.html#meta) element to indicate where the current master source of the resource can be found.

**Requirements:** Allows the Group to be referenced by a single globally unique identifier.

**Cardinality:** 0..1

**Type:** [uri](/uri)

**Summary:** true

**Constraints:** cnl-1 | warning | URL should not contain | or # - these characters make processing canonical references problematic | exists() implies matches('^[^|# ]+$')

**Mappings:** w5=FiveWs.identifier


<a id="Group.identifier"></a>

## Group.identifier
Business Identifier for this Group

**Definition:** Business identifiers assigned to this participant by one of the applications involved.  These identifiers remain constant as the resource is updated and propagates from server to server.

**Comments:** Note: This is a business identifier, not a resource identifier (see [discussion](resource.html#identifiers)).  It is best practice for the identifier to only appear on a single resource instance, however business practices may occasionally dictate that multiple resource instances with the same identifier can exist - possibly even with different resource types.

**Requirements:** Allows identification of the group as it is known by various participating systems and in a way that remains consistent across servers.

**Cardinality:** 0..*

**Type:** [Identifier](/Identifier)

**Summary:** true

**Mappings:** w5=FiveWs.identifier; rim=unique(./id[displayable="true" and scope="OBJ"]); interface=Participant.identifier


<a id="Group.version"></a>

## Group.version
Business version of the Group

**Definition:** The identifier that is used to identify this version of the Group when it is referenced in a specification, model, design or instance. This is an arbitrary value managed by the Group author and is not expected to be globally unique. For example, it might be a timestamp (e.g. yyyymmdd) if a managed version is not available. There is also no expectation that versions can be placed in a lexicographical sequence without additional knowledge.

**Comments:** There may be different Groups that have the same url but different versions.  The version can be appended to the url in a reference to allow a reference to a particular business version of the Group with the format [url]|[version]. The version SHOULD NOT contain a '#' - see [Business Version](resource.html#bv-format).

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true

**Mappings:** w5=FiveWs.version


<a id="Group.versionAlgorithm[x]"></a>

## Group.versionAlgorithm[x]
How to compare versions

**Definition:** Indicates the mechanism used to compare versions to determine which is more current.

**Comments:** If set as a string, this is a FHIRPath expression that has two additional context variables passed in - %version1 and %version2 and will return a negative number if version1 is newer, a positive number if version2 and a 0 if the version ordering can't be successfully be determined.

**Cardinality:** 0..1

**Type:** [string](/string), [Coding](/Coding)

**Binding:** extensible:[version-algorithm](/valueset-version-algorithm)

**Summary:** true


<a id="Group.name"></a>

## Group.name
Label for Group

**Definition:** A label assigned to the group for human identification and communication.

**Requirements:** Used to identify the group in human communication.

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true

**Mappings:** rim=./name[type="ST"]; interface=Participant.name


<a id="Group.title"></a>

## Group.title
Name for this Group (human friendly)

**Definition:** A short, descriptive, user-friendly title for the Group.

**Comments:** This name does not need to be machine-processing friendly and may contain punctuation, white-space, etc.

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true


<a id="Group.status"></a>

## Group.status
draft | active | retired | unknown

**Definition:** The current state of this Group.

**Comments:** A nominal state-transition diagram can be found in the [Definition pattern](definition.html#statemachine) documentation.

Unknown does not represent 'other' - one of the defined statuses must apply. Unknown is used when the authoring system is not sure what the current status is.

See guidance around (not) making local changes to elements [here](canonicalresource.html#localization).

**Requirements:** Enables tracking the life-cycle of the content and filtering of Groups that are appropriate for use versus not.

**Cardinality:** 0..1

**Type:** [code](/code)

**Binding:** required:[publication-status](/valueset-publication-status)

**Summary:** true

**Is Modifier:** true (Reason: This is labeled as "Is Modifier" because applications should not use a retired Group without due consideration)

**Mappings:** w5=FiveWs.status


<a id="Group.experimental"></a>

## Group.experimental
For testing only - never for real usage

**Definition:** A Boolean value to indicate that this Group is authored for testing purposes (or education/evaluation/marketing) and no version of this resource will ever be intended for genuine usage.

**Comments:** Allows filtering of Groups that are appropriate for use versus not. Experimental resources might include example instances in implementation guides, instances created solely for testing purposes, etc. If experimental is 'true' for any version of a resource, it should be true for all versions of the resource.  (If experimental changes, then it is being misused or a resource that was never intended for real-world use has unexpectedly changed its purpose.).

Experimental resources are not expected to be stable and may well have breaking changes without a corresponding change to the 'version' element.

**Requirements:** Enables experimental content to be developed following the same lifecycle that would be used for a production-level Group.

**Meaning if Missing:** If absent, this resource is treated as though it is not experimental.

**Cardinality:** 0..1

**Type:** [boolean](/boolean)

**Summary:** true

**Mappings:** w5=FiveWs.class


<a id="Group.date"></a>

## Group.date
Date last changed

**Definition:** The date (and optionally time) when the Group was last significantly changed. The date must change when the business version changes and it must change if the status code changes. In addition, it should change when the substantive content of the Group changes.

**Comments:** The date is often not tracked until the resource is published, but may be present on draft content. Note that this is not the same as the resource last-modified-date, since the resource may be a secondary representation of the Group. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource.

See guidance around (not) making local changes to elements [here](canonicalresource.html#localization).

**Aliases:** Revision Date

**Cardinality:** 0..1

**Type:** [dateTime](/dateTime)

**Summary:** true

**Mappings:** w5=FiveWs.recorded


<a id="Group.publisher"></a>

## Group.publisher
Name of the publisher/steward (organization or individual)

**Definition:** The name of the organization or individual responsible for the release and ongoing maintenance of the Group.

**Comments:** Usually an organization but may be an individual. The publisher (or steward) of the Group is the organization or individual primarily responsible for the maintenance and upkeep of the Group. This is not necessarily the same individual or organization that developed and initially authored the content. The publisher is the primary point of contact for questions or issues with the Group. This item SHOULD be populated unless the information is available from context.

**Requirements:** Helps establish the "authority/credibility" of the Group.  May also allow for contact.

**Cardinality:** 0..1

**Type:** [string](/string)

**Summary:** true

**Mappings:** w5=FiveWs.witness


<a id="Group.contact"></a>

## Group.contact
Contact details for the publisher

**Definition:** Contact details to assist a user in finding and communicating with the publisher.

**Comments:** May be a web site, an email address, a telephone number, etc.

See guidance around (not) making local changes to elements [here](canonicalresource.html#localization).

**Cardinality:** 0..*

**Type:** [ContactDetail](/ContactDetail)

**Summary:** true


<a id="Group.description"></a>

## Group.description
Natural language description of the group

**Definition:** Explanation of what the group represents and how it is intended to be used.

**Cardinality:** 0..1

**Type:** [markdown](/markdown)


<a id="Group.useContext"></a>

## Group.useContext
The context that the content is intended to support

**Definition:** The content was developed with a focus and intent of supporting the contexts that are listed. These contexts may be general categories (gender, age, ...) or may be references to specific programs (insurance plans, studies, ...) and may be used to assist with indexing and searching for appropriate Groups.

**Comments:** When multiple useContexts are specified, there is no expectation that all or even any of the contexts apply.

**Requirements:** Assist in searching for appropriate content.

**Cardinality:** 0..*

**Type:** [UsageContext](/UsageContext)

**Summary:** true


<a id="Group.purpose"></a>

## Group.purpose
Why this Group is defined

**Definition:** Explanation of why this Group is needed and why it has been designed as it has.

**Comments:** This element does not describe the usage of the Group. Instead, it provides traceability of "why" the resource is either needed or "why" it is defined as it is.  This may be used to point to source materials or specifications that drove the structure of this Group.

**Cardinality:** 0..1

**Type:** [markdown](/markdown)

**Mappings:** objimpl=no-gen-base; w5=FiveWs.why[x]


<a id="Group.copyright"></a>

## Group.copyright
Notice about intellectual property ownership, can include restrictions on use

**Definition:** A copyright statement relating to the Group and/or its contents. Copyright statements are notices of intellectual property ownership and can include restrictions on the use and publishing of the Group.

**Comments:** The short copyright declaration (e.g. (c) '2015+ xyz organization') should be sent in the copyrightLabel element without the copyright prefix (i.e., do not include '(c)' or the symbol).

**Requirements:** Consumers must be able to determine any legal restrictions on the use of the Group and/or its content.

**Aliases:** License, Restrictions

**Cardinality:** 0..1

**Type:** [markdown](/markdown)

**Mappings:** objimpl=no-gen-base


<a id="Group.copyrightLabel"></a>

## Group.copyrightLabel
Copyright holder and year(s)

**Definition:** A short string (<50 characters), suitable for inclusion in a page footer that identifies the copyright holder, effective period, and optionally whether rights are restricted. (e.g. 'All rights reserved', 'Some rights reserved').

**Comments:** The copyright symbol and the '(c)' textual representation SHOULD NOT be included in this string. It will be added by software when rendering the notation. Full details about licensing, restrictions, warrantees, etc. goes in the more general 'copyright' element.

**Requirements:** Defines the content expected to be rendered in all representations of the artifact.

**Cardinality:** 0..1

**Type:** [string](/string)


<a id="Group.type"></a>

## Group.type
person | animal | practitioner | device | careteam | healthcareservice | location | organization | relatedperson | specimen | medication | medicinalproductdefinition | substance | substancedefinition | biologicallyDerivedProduct | nutritionProduct

**Definition:** Identifies the broad classification of the kind of resources the group includes.

**Comments:** Group members SHALL be of the appropriate resource type (Patient for person or animal; or Practitioner, PractitionerRole, Device, CareTeam, HealthcareService, Location, Organization, RelatedPerson, Specimen, Medication, Substance, BiologicallyDerivedProduct, or NutritionProduct for the other types.), or a Group of the resources of the appropriate type.

**Requirements:** Identifies what type of resources the group is made up of.

**Conditions:** grp-2

**Cardinality:** 0..1

**Type:** [code](/code)

**Binding:** required:[group-type](/valueset-group-type)

**Summary:** true

**Mappings:** w5=FiveWs.class; rim=person: ./classCode="PSN"  animal: ./classCode="ANM"  device: ./classCode="DEV"  medication: ./classCode="MMAT" and ./playedRole[isNormalRole() and classCode="THER"]  food: ./classCode="FOOD"


<a id="Group.membership"></a>

## Group.membership
definitional | conceptual | enumerated

**Definition:** Basis for membership in the Group:

* 'definitional': The Group.characteristics specified are both necessary and sufficient to determine membership. All entities that meet the criteria are considered to be members of the group, whether referenced by the group or not. If members are present, they are individuals that happen to be known as meeting the Group.characteristics. The list cannot be presumed to be complete.
* 'conceptual': The Group.characteristics specified are both necessary and sufficient to determine membership. The 'conceptual' Group is a 'definitional' Group in which the Group.type is not bound to FHIR types.
* 'enumerated': The Group.characteristics are necessary but not sufficient to determine membership. Membership is determined by being listed as one of the Group.member.

**Requirements:** There are use-cases for groups that define specific collections of individuals, and other groups that define "types" of intended individuals.  The requirements for both kinds of groups are similar, so we use a single resource, distinguished by this element.

**Conditions:** grp-2

**Cardinality:** 1..1

**Type:** [code](/code)

**Binding:** required:[group-membership-basis](/valueset-group-membership-basis)

**Summary:** true


<a id="Group.code"></a>

## Group.code
Use of the Group (and by implication, kind of members)

**Definition:** A code that describes the use of the group. The use of the group usually dictates what kind of entities can be members of the group.

**Comments:** The types of entities that can be members needs to align with Group.type

**Cardinality:** 0..1

**Type:** [CodeableConcept](/CodeableConcept)

**Binding:** extensible:[group-code](/valueset-group-code)

**Summary:** true

**Mappings:** w5=FiveWs.what[x]; rim=./code


<a id="Group.quantity"></a>

## Group.quantity
Number of members

**Definition:** A count of the number of resource instances that are part of the group.

**Comments:** Note that the quantity may be less than the number of members if some of the members are not active.

**Requirements:** Group size is a common defining characteristic.

**Cardinality:** 0..1

**Type:** [unsignedInt](/unsignedInt)

**Summary:** true

**Mappings:** rim=./quantity


<a id="Group.managingEntity"></a>

## Group.managingEntity
Entity that is the custodian of the Group's definition

**Definition:** Entity responsible for defining and maintaining Group characteristics and/or registered members.

**Comments:** This does not strictly align with ownership of a herd or flock, but may suffice to represent that relationship in simple cases. More complex cases will require an extension.

**Cardinality:** 0..1

**Type:** Reference([Organization](/Organization), [RelatedPerson](/RelatedPerson), [Practitioner](/Practitioner), [PractitionerRole](/PractitionerRole))

**Summary:** true

**Mappings:** w5=FiveWs.witness


<a id="Group.combinationMethod"></a>

## Group.combinationMethod
all-of | any-of | at-least | at-most | except-subset

**Definition:** Used to specify how two or more characteristics are combined.

**Meaning if Missing:** If absent, this element is treated as though it had been set to 'all-of'

**Cardinality:** 0..1

**Type:** [code](/code)

**Binding:** required:[group-characteristic-combination](/valueset-group-characteristic-combination)

**Summary:** true

**Is Modifier:** true (Reason: Changing the combinationMethod from all-of to any other value changes the interpretation of multiple characteristics.)


<a id="Group.combinationThreshold"></a>

## Group.combinationThreshold
Provides the value of "n" when "at-least" or "at-most" codes are used

**Definition:** Provides the value of "n" when "at-least" or "at-most" codes are used for combinationMethod.

**Cardinality:** 0..1

**Type:** [positiveInt](/positiveInt)


<a id="Group.characteristic"></a>

## Group.characteristic
Include / Exclude group members by Trait

**Definition:** Identifies traits whose presence r absence is shared by members of the group.

**Comments:** Some subset (as determined by combinationMethod) of the identified characteristics must be true for an entity to a member of the group.

**Requirements:** Needs to be a generic mechanism for identifying what individuals can be part of a group.

**Cardinality:** 0..*

**Type:** [BackboneElement](/BackboneElement)

**Summary:** true

**Mappings:** rim=./playedRole[isNormalRole()]/participation[isNormalParticipation() and typeCode="SBJ"]/act[isNormalAct and classCode="OBS" and moodCode="EVN"]


<a id="Group.characteristic.code"></a>

## Group.characteristic.code
Kind of characteristic

**Definition:** A code that identifies the kind of trait being asserted.

**Requirements:** Need a formal way of identifying the characteristic being described.

**Cardinality:** 1..1

**Type:** [CodeableConcept](/CodeableConcept)

**Binding:** example:[example-characteristic-codes](/valueset-example-characteristic-codes)

**Summary:** true

**Mappings:** rim=./code


<a id="Group.characteristic.value[x]"></a>

## Group.characteristic.value[x]
Value held by characteristic

**Definition:** The value of the trait that holds (or does not hold - see 'exclude') for members of the group.

**Comments:** For Range, it means members of the group have a value that falls somewhere within the specified range.

**Requirements:** The value of the characteristic is what determines group membership.

**Cardinality:** 1..1

**Type:** [CodeableConcept](/CodeableConcept), [boolean](/boolean), [Quantity](/Quantity), [Range](/Range), [Reference](/Reference), [uri](/uri), [Expression](/Expression)

**Summary:** true

**Mappings:** rim=./value


<a id="Group.characteristic.exclude"></a>

## Group.characteristic.exclude
Group includes or excludes

**Definition:** If true, indicates the characteristic is one that is NOT held by members of the group.

**Comments:** This is labeled as "Is Modifier" because applications cannot wrongly include excluded members as included or vice versa.

**Requirements:** Sometimes group membership is determined by characteristics not possessed.

**Cardinality:** 1..1

**Type:** [boolean](/boolean)

**Summary:** true

**Mappings:** rim=./valueNegationInd


<a id="Group.characteristic.description"></a>

## Group.characteristic.description
Natural language description of the characteristic

**Definition:** A short, natural language description of the characteristic that could be used to communicate the criteria to an end-user.

**Requirements:** Need to be able to describe characteristics in natural language so that end users can understand the criteria.

**Cardinality:** 0..1

**Type:** [markdown](/markdown)


<a id="Group.characteristic.method"></a>

## Group.characteristic.method
Method for how the characteristic value was determined

**Definition:** Method for how the characteristic value was determined.

**Cardinality:** 0..*

**Type:** [CodeableConcept](/CodeableConcept)

**Binding:** example:[definition-method](/valueset-definition-method)


<a id="Group.characteristic.formula"></a>

## Group.characteristic.formula
Formal algorithm to derive the value

**Definition:** A CQL, FHIRPath, or other expression that is used to generate the value for this characteristic.

**Cardinality:** 0..1

**Type:** [Expression](/Expression)


<a id="Group.characteristic.determiner"></a>

## Group.characteristic.determiner
Who determines the value

**Definition:** The entity who is expected to evaluate the characteristic value for candidate group members.

**Comments:** The expectation is that the determiner is someone who matches the characteristics specified by the referenced entity, not necessarily that the actual reference in the instance is to the entity.  For example, if specifying a PractitionerRole with just a PractitionerRole.type, it's fine for any PractitionerRole that matches or specializes that type to do the determination.

**Cardinality:** 0..1

**Type:** Reference([Practitioner](/Practitioner), [PractitionerRole](/PractitionerRole), [Organization](/Organization), [Device](/Device), [DeviceDefinition](/DeviceDefinition))


<a id="Group.characteristic.offset"></a>

## Group.characteristic.offset
Reference point for comparison

**Definition:** Defines the reference point for comparison when other than 0.

**Cardinality:** 0..1

**Type:** [CodeableConcept](/CodeableConcept)

**Binding:** example:[characteristic-offset](/valueset-characteristic-offset)

**Summary:** true

**Is Modifier:** true (Reason: If offset is present it must be included to interpret the characteristic value.)


<a id="Group.characteristic.instances[x]"></a>

## Group.characteristic.instances[x]
Number of occurrences meeting the characteristic

**Definition:** Number of occurrences meeting the characteristic.

**Cardinality:** 0..1

**Type:** [unsignedInt](/unsignedInt), [Range](/Range)

**Constraints:** grp-1 | error | Ranges have to be positive | ($this is Range) implies ((low.empty() or ((low.code.exists() or low.value.empty()) and (low.system.empty() or low.system = %ucum) and (low.code.empty() or low.code = '1') and (low.value.empty() or low.value.hasValue().not() or low.value.toString().contains('.').not()) and (low.value.empty() or low.value.hasValue().not() or low.value >= 0))) and (high.empty() or ((high.code.exists() or high.value.empty()) and (high.system.empty() or high.system = %ucum) and (high.code.empty() or high.code = '1') and (high.value.empty() or high.value.hasValue().not() or high.value.toString().contains('.').not()) and (high.value.empty() or high.value.hasValue().not() or high.value >= 0))))


<a id="Group.characteristic.duration[x]"></a>

## Group.characteristic.duration[x]
Length of time in which the characteristic is met

**Definition:** Length of time in which the characteristic is met.

**Cardinality:** 0..1

**Type:** [Duration](/Duration), [Range](/Range)


<a id="Group.characteristic.period"></a>

## Group.characteristic.period
Period over which characteristic is tested

**Definition:** The period over which the characteristic is tested; e.g. the patient had an operation during the month of June.

**Cardinality:** 0..1

**Type:** [Period](/Period)


<a id="Group.characteristic.timing"></a>

## Group.characteristic.timing
Timing in which the characteristic is determined

**Definition:** Timing in which the characteristic is determined.

**Cardinality:** 0..*

**Type:** [RelativeTime](/RelativeTime)


<a id="Group.member"></a>

## Group.member
Who or what is in group

**Definition:** Identifies the resource instances that are members of the group.

**Requirements:** Often the only thing of interest about a group is "who's in it".

**Cardinality:** 0..*

**Type:** [BackboneElement](/BackboneElement)

**Mappings:** rim=./scopedRole[isNormalRole() and classCode="MBR"]/player; w5=FiveWs.subject


<a id="Group.member.entity"></a>

## Group.member.entity
Reference to the group member

**Definition:** A reference to the entity that is a member of the group. Must be consistent with Group.type. If the entity is another group, then the type must be the same.

**Cardinality:** 1..1

**Type:** Reference([CareTeam](/CareTeam), [Device](/Device), [Group](/Group), [HealthcareService](/HealthcareService), [Location](/Location), [Organization](/Organization), [Patient](/Patient), [Practitioner](/Practitioner), [PractitionerRole](/PractitionerRole), [RelatedPerson](/RelatedPerson), [Specimen](/Specimen), [Medication](/Medication), [MedicinalProductDefinition](/MedicinalProductDefinition), [Substance](/Substance), [SubstanceDefinition](/SubstanceDefinition), [BiologicallyDerivedProduct](/BiologicallyDerivedProduct), [NutritionProduct](/NutritionProduct))


<a id="Group.member.involvement"></a>

## Group.member.involvement
Code that describes how user is part of the group

**Definition:** A code that describes how a user is involved in the group. Some groups (e.g. exposure-group) typically don't have variance between members, or it is not tracked, while for other groups (e.g. family, household) this may be meaningful.

**Comments:** See [Relationships inside the group](group.html#relationships) for more detailed family relationships.

**Cardinality:** 0..*

**Type:** [CodeableConcept](/CodeableConcept)

**Binding:** example:[group-involvement-set](/valueset-group-involvement-set)


<a id="Group.member.period"></a>

## Group.member.period
Period member belonged to the group

**Definition:** The period that the member was in the group, if known.

**Requirements:** Need to track who was in a group at a  particular time.

**Meaning if Missing:** The member is in the group at this time

**Cardinality:** 0..1

**Type:** [Period](/Period)


<a id="Group.member.inactive"></a>

## Group.member.inactive
If member is no longer in group

**Definition:** A flag to indicate that the member is no longer in the group, but previously may have been a member.

**Requirements:** Sometimes you don't know when someone stopped being in a group, but not when.

**Meaning if Missing:** Members are considered active unless explicitly specified otherwise

**Cardinality:** 0..1

**Type:** [boolean](/boolean)