Represents a defined collection of entities that may be discussed or acted upon collectively but which are not expected to act collectively, and are not formally or legally recognized; i.e. a collection of entities that isn't an Organization.

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.

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of its narrative along with other profiles, value sets, etc.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, nor can they have their own independent transaction scope. This is allowed to be a Parameters resource if and only if it is referenced by a resource that provides context/meaning.

This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags in their meta elements, but SHALL NOT have security labels.

An Extension

STU3: Group.actual (new:boolean)

Element Group.actual has a context of Group based on following the parent source element upwards and mapping to Group. Element Group.actual has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

Indicates whether the record for the group is available for use or is merely being retained for historical purposes.

Need to be able to mark a group record as not to be used because it was created in error or is otherwise no longer available (e.g. a herd that no longer exists).

Identifies the broad classification of the kind of resources the group includes.

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

Types of resources that are part of group.

Identifies what type of resources the group is made up of.

An Extension

STU3: Group.type additional codes

Element Group.type is mapped to FHIR R5 element Group.type as RelatedTo. The mappings for Group.type do not allow expression of the necessary codes, per the bindings on the source and target. Group members SHALL be of the appropriate resource type (Patient for person or animal; or Practitioner, Device, Medicaiton or Substance for the other types.).

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.
• 'enumerated': The Group.characteristics are necessary but not sufficient to determine membership. Membership is determined by being listed as one of the Group.member.

The basis for membership in a group

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.

STU3: Group.meta additional types (Meta) additional types from child elements (lastUpdated, profile, security, tag, versionId)

Element Group.meta is mapped to FHIR R5 element Group.meta as SourceIsBroaderThanTarget. The mappings for Group.meta do not cover the following types: Meta. The mappings for Group.meta do not cover the following types based on type expansion: lastUpdated, profile, security, tag, versionId.

STU3: Group.text additional types (Narrative) additional types from child elements (div, status)

Element Group.text is mapped to FHIR R5 element Group.text as SourceIsBroaderThanTarget. The mappings for Group.text do not cover the following types: Narrative. The mappings for Group.text do not cover the following types based on type expansion: div, status. Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded in formation is added later.

STU3: Group.actual (new:boolean)

Element Group.actual has a context of Group based on following the parent source element upwards and mapping to Group. Element Group.actual has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

STU3: Group.identifier additional types (Identifier) additional types from child elements (assigner, period, system, type, use, value)

Element Group.identifier is mapped to FHIR R5 element Group.identifier as SourceIsBroaderThanTarget. The mappings for Group.identifier do not cover the following types: Identifier. The mappings for Group.identifier do not cover the following types based on type expansion: assigner, period, system, type, use, value.

STU3: Group.type additional codes

Element Group.type is mapped to FHIR R5 element Group.type as RelatedTo. The mappings for Group.type do not allow expression of the necessary codes, per the bindings on the source and target. Group members SHALL be of the appropriate resource type (Patient for person or animal; or Practitioner, Device, Medicaiton or Substance for the other types.).

STU3: Group.name

Element Group.name is mapped to FHIR R5 element Group.name as Equivalent. An externally-defined extension that has been mapped as the representation of FHIR STU3 element Group.name: http://hl7.org/fhir/StructureDefinition/artifact-name.

STU3: Group.characteristic.value[x] additional types (Range)

Element Group.characteristic.value[x] is mapped to FHIR R5 element Group.characteristic.value[x] as SourceIsBroaderThanTarget. The mappings for Group.characteristic.value[x] do not cover the following types: Range. The target context Group.characteristic.value[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Group.characteristic. For Range, it means members of the group have a value that falls somewhere within the specified range.

STU3: Group.characteristic.period additional types (Period) additional types from child elements (end, start)

Element Group.characteristic.period is mapped to FHIR R5 element Group.characteristic.period as SourceIsBroaderThanTarget. The mappings for Group.characteristic.period do not cover the following types: Period. The mappings for Group.characteristic.period do not cover the following types based on type expansion: end, start.

STU3: Group.member.entity

Element Group.member.entity is mapped to FHIR R5 element Group.member.entity as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR STU3 element Group.member.entity with unmapped reference targets: Device, Medication, Patient, Practitioner, Substance.

STU3: Group.member.period additional types (Period) additional types from child elements (end, start)

Element Group.member.period is mapped to FHIR R5 element Group.member.period as SourceIsBroaderThanTarget. The mappings for Group.member.period do not cover the following types: Period. The mappings for Group.member.period do not cover the following types based on type expansion: end, start.

Represents a defined collection of entities that may be discussed or acted upon collectively but which are not expected to act collectively, and are not formally or legally recognized; i.e. a collection of entities that isn't an Organization.

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.

The logical id of the resource, as used in the URL for the resource. Once assigned, this value never changes.

Within the context of the FHIR RESTful interactions, the resource has an id except for cases like the create and conditional update. Otherwise, the use of the resouce id depends on the given use case.

The metadata about the resource. This is content that is maintained by the infrastructure. Changes to the content might not always be associated with version changes to the resource.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

STU3: Group.meta additional types (Meta) additional types from child elements (lastUpdated, profile, security, tag, versionId)

Element Group.meta is mapped to FHIR R5 element Group.meta as SourceIsBroaderThanTarget. The mappings for Group.meta do not cover the following types: Meta. The mappings for Group.meta do not cover the following types based on type expansion: lastUpdated, profile, security, tag, versionId.

The version specific identifier, as it appears in the version portion of the URL. This value changes when the resource is created, updated, or deleted.

The server assigns this value, and ignores what the client specifies, except in the case that the server is imposing version integrity on updates/deletes.

When the resource last changed - e.g. when the version changed.

This element is generally omitted in instances submitted in a PUT or POST. Instead, it is populated in the response instance and when retrieving information using a GET. The server / resource manager sets this value; what a client provides is irrelevant. This is equivalent to the HTTP Last-Modified and SHOULD have the same value on a read interaction.

A uri that identifies the source system of the resource. This provides a minimal amount of Provenance information that can be used to track or differentiate the source of information in the resource. The source may identify another FHIR server, document, message, database, etc.

The exact use of the source (and the possible implied Provenance.entity.role and agent.role) is left to implementer discretion. Only one nominated source is allowed; for additional provenance details, a full Provenance resource should be used. The source may correspond to Provenance.entity.what[x] or Provenance.agent.who[x], though it may be a more general or abstract reference.

This element can be used to indicate where the current master source of a resource that has a canonical URL if the resource is no longer hosted at the canonical URL.

A list of profiles (references to StructureDefinition resources) that this resource claims to conform to. The URL is a reference to StructureDefinition.url.

It is up to the server and/or other infrastructure of policy to determine whether/how these claims are verified and/or updated over time. The list of profile URLs is a set.

Security labels applied to this resource. These tags connect specific resources to the overall security policy and infrastructure.

The security labels can be updated without changing the stated version of the resource. The list of security labels is a set. Uniqueness is based the system/code, and version and display are ignored.

Unless not suitable, these codes SHALL be taken from AllSecurityLabels
(extensible to http://hl7.org/fhir/ValueSet/security-labels|5.0.0)

Security Labels from the Healthcare Privacy and Security Classification System.

Tags applied to this resource. Tags are intended to be used to identify and relate resources to process and workflow, and applications are not required to consider the tags when interpreting the meaning of a resource.

The tags can be updated without changing the stated version of the resource. The list of tags is a set. Uniqueness is based the system/code, and version and display are ignored.

Codes that represent various types of tags, commonly workflow-related; e.g. "Needs review by Dr. Jones".

A reference to a set of rules that were followed when the resource was constructed, and which must be understood when processing the content. Often, this is a reference to an implementation guide that defines the special rules along with other profiles etc.

Asserting this rule set restricts the content to be only understood by a limited set of trading partners. This inherently limits the usefulness of the data in the long term. However, the existing health eco-system is highly fractured, and not yet ready to define, collect, and exchange data in a generally computable sense. Wherever possible, implementers and/or specification writers should avoid using this element. Often, when used, the URL is a reference to an implementation guide that defines these special rules as part of its narrative along with other profiles, value sets, etc.

The base language in which the resource is written.

Language is provided to support indexing and accessibility (typically, services such as text to speech use the language tag). The html language tag in the narrative applies to the narrative. The language tag on the resource may be used to specify the language of other presentations generated from the data in the resource. Not all the content has to be in the base language. The Resource.language should not be assumed to apply to the narrative automatically. If a language is specified, it should it also be specified on the div element in the html (see rules in HTML5 for information about the relationship between xml:lang and the html lang attribute).

IETF language tag for a human language

A human-readable narrative that contains a summary of the resource and can be used to represent the content of the resource to a human. The narrative need not encode all the structured data, but is required to contain sufficient detail to make it "clinically safe" for a human to just read the narrative. Resource definitions may define what content should be represented in the narrative to ensure clinical safety.

Contained resources do not have a narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded information is added later.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

STU3: Group.text additional types (Narrative) additional types from child elements (div, status)

Element Group.text is mapped to FHIR R5 element Group.text as SourceIsBroaderThanTarget. The mappings for Group.text do not cover the following types: Narrative. The mappings for Group.text do not cover the following types based on type expansion: div, status. Contained resources do not have narrative. Resources that are not contained SHOULD have a narrative. In some cases, a resource may only have text with little or no additional discrete data (as long as all minOccurs=1 elements are satisfied). This may be necessary for data from legacy systems where information is captured as a "text blob" or where text is additionally entered raw or narrated and encoded in formation is added later.

The status of the narrative - whether it's entirely generated (from just the defined data or the extensions too), or whether a human authored it and it may contain additional data.

The status of a resource narrative.

The actual narrative content, a stripped down version of XHTML.

The contents of the html element are an XHTML fragment containing only the basic html formatting elements described in chapters 7-11 and 15 of the HTML 4.0 standard, <a> elements (either name or href), images and internally contained stylesheets. The XHTML content SHALL NOT contain a head, a body, external stylesheet references, scripts, forms, base/link/xlink, frames, iframes and objects.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, nor can they have their own independent transaction scope. This is allowed to be a Parameters resource if and only if it is referenced by a resource that provides context/meaning.

This should never be done when the content can be identified properly, as once identification is lost, it is extremely difficult (and context dependent) to restore it again. Contained resources may have profiles and tags in their meta elements, but SHALL NOT have security labels.

An Extension

STU3: Group.actual (new:boolean)

Element Group.actual has a context of Group based on following the parent source element upwards and mapping to Group. Element Group.actual has no mapping targets in FHIR R5. Typically, this is because the element has been added (is a new element).

May be used to represent additional information that is not part of the basic definition of the resource and that modifies the understanding of the element that contains it and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer is allowed to define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

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.

Note: This is a business identifier, not a resource identifier (see discussion). 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.

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

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

STU3: Group.identifier additional types (Identifier) additional types from child elements (assigner, period, system, type, use, value)

Element Group.identifier is mapped to FHIR R5 element Group.identifier as SourceIsBroaderThanTarget. The mappings for Group.identifier do not cover the following types: Identifier. The mappings for Group.identifier do not cover the following types based on type expansion: assigner, period, system, type, use, value.

The purpose of this identifier.

Applications can assume that an identifier is permanent unless it explicitly says that it is temporary.

Identifies the purpose for this identifier, if known .

Allows the appropriate identifier for a particular context of use to be selected from among a set of identifiers.

A coded type for the identifier that can be used to determine which identifier to use for a specific purpose.

This element deals only with general categories of identifiers. It SHOULD not be used for codes that correspond 1..1 with the Identifier.system. Some identifiers may fall into multiple categories due to common usage. Where the system is known, a type is unnecessary because the type is always part of the system definition. However systems often need to handle identifiers where the system is not known. There is not a 1:1 relationship between type and system, since many different systems have the same type.

A coded type for an identifier that can be used to determine which identifier to use for a specific purpose.

Allows users to make use of identifiers when the identifier system is not known.

Establishes the namespace for the value - that is, an absolute URL that describes a set values that are unique.

Identifier.system is always case sensitive.

There are many sets of identifiers. To perform matching of two identifiers, we need to know what set we're dealing with. The system identifies a particular set of unique identifiers.

The portion of the identifier typically relevant to the user and which is unique within the context of the system.

If the value is a full URI, then the system SHALL be urn:ietf:rfc:3986. The value's primary purpose is computational mapping. As a result, it may be normalized for comparison purposes (e.g. removing non-significant whitespace, dashes, etc.) A value formatted for human display can be conveyed using the http://hl7.org/fhir/StructureDefinition/rendered-value). 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.

Time period during which identifier is/was valid for use.

Organization that issued/manages the identifier.

The Identifier.assigner may omit the .reference element and only contain a .display element reflecting the name or other textual information about the assigning organization.

Indicates whether the record for the group is available for use or is merely being retained for historical purposes.

Need to be able to mark a group record as not to be used because it was created in error or is otherwise no longer available (e.g. a herd that no longer exists).

Identifies the broad classification of the kind of resources the group includes.

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

Types of resources that are part of group.

Identifies what type of resources the group is made up of.

unique id for the element within a resource (for internal references)

An Extension

STU3: Group.type additional codes

Element Group.type is mapped to FHIR R5 element Group.type as RelatedTo. The mappings for Group.type do not allow expression of the necessary codes, per the bindings on the source and target. Group members SHALL be of the appropriate resource type (Patient for person or animal; or Practitioner, Device, Medicaiton or Substance for the other types.).

Primitive value for code

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.
• 'enumerated': The Group.characteristics are necessary but not sufficient to determine membership. Membership is determined by being listed as one of the Group.member.

The basis for membership in a group

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.

Provides a specific type of resource the group includes; e.g. "cow", "syringe", etc.

This would generally be omitted for Person resources.

Kind of particular resource; e.g. cow, syringe, lake, etc.

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

Used to identify the group in human communication.

unique id for the element within a resource (for internal references)

An Extension

STU3: Group.name

Element Group.name is mapped to FHIR R5 element Group.name as Equivalent. An externally-defined extension that has been mapped as the representation of FHIR STU3 element Group.name: http://hl7.org/fhir/StructureDefinition/artifact-name.

The actual value

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

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

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

Group size is a common defining characteristic.

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

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.

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

All the identified characteristics must be true for an entity to a member of the group.

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

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

STU3: Group.characteristic.value[x] additional types (Range)

Element Group.characteristic.value[x] is mapped to FHIR R5 element Group.characteristic.value[x] as SourceIsBroaderThanTarget. The mappings for Group.characteristic.value[x] do not cover the following types: Range. The target context Group.characteristic.value[x] is a choice-type element and cannot directly hold extensions. The context is moved up to parent element Group.characteristic. For Range, it means members of the group have a value that falls somewhere within the specified range.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

A code that identifies the kind of trait being asserted.

List of characteristics used to describe group members; e.g. gender, age, owner, location, etc.

Need a formal way of identifying the characteristic being described.

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

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

Value of descriptive member characteristic; e.g. red, male, pneumonia, Caucasian, etc.

The value of the characteristic is what determines group membership.

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

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

Sometimes group membership is determined by characteristics not possessed.

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

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

STU3: Group.characteristic.period additional types (Period) additional types from child elements (end, start)

Element Group.characteristic.period is mapped to FHIR R5 element Group.characteristic.period as SourceIsBroaderThanTarget. The mappings for Group.characteristic.period do not cover the following types: Period. The mappings for Group.characteristic.period do not cover the following types based on type expansion: end, start.

The start of the period. The boundary is inclusive.

If the low element is missing, the meaning is that the low boundary is not known.

The end of the period. If the end of the period is missing, it means no end was known or planned at the time the instance was created. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.

The end value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has an end value of 2012-02-03.

Identifies the resource instances that are members of the group.

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

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

May be used to represent additional information that is not part of the basic definition of the element. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

May be used to represent additional information that is not part of the basic definition of the element and that modifies the understanding of the element in which it is contained and/or the understanding of the containing element's descendants. Usually modifier elements provide negation or qualification. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. Applications processing a resource are required to check for modifier extensions.

Modifier extensions SHALL NOT change the meaning of any elements on Resource or DomainResource (including cannot change the meaning of modifierExtension itself).

There can be no stigma associated with the use of extensions by any application, project, or standard - regardless of the institution or jurisdiction that uses or defines the extensions. The use of extensions is what allows the FHIR specification to retain a core level of simplicity for everyone.

Modifier extensions allow for extensions that cannot be safely ignored to be clearly distinguished from the vast majority of extensions which can be safely ignored. This promotes interoperability by eliminating the need for implementers to prohibit the presence of extensions. For further information, see the definition of modifier extensions.

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.

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

STU3: Group.member.entity

Element Group.member.entity is mapped to FHIR R5 element Group.member.entity as SourceIsBroaderThanTarget. The standard extension alternate-reference has been mapped as the representation of FHIR STU3 element Group.member.entity with unmapped reference targets: Device, Medication, Patient, Practitioner, Substance.

A reference to a location at which the other resource is found. The reference may be a relative reference, in which case it is relative to the service base URL, or an absolute URL that resolves to the location where the resource is found. The reference may be version specific or not. If the reference is not to a FHIR RESTful server, then it should be assumed to be version specific. Internal fragment references (start with '#') refer to contained resources.

Using absolute URLs provides a stable scalable approach suitable for a cloud/web context, while using relative/logical references provides a flexible approach suitable for use when trading across closed eco-system boundaries. Absolute URLs do not need to point to a FHIR RESTful server, though this is the preferred approach. If the URL conforms to the structure "[type]/[id]" then it should be assumed that the reference is to a FHIR RESTful server.

The expected type of the target of the reference. If both Reference.type and Reference.reference are populated and Reference.reference is a FHIR URL, both SHALL be consistent.

The type is the Canonical URL of Resource Definition that is the type this reference refers to. References are URLs that are relative to http://hl7.org/fhir/StructureDefinition/ e.g. "Patient" is a reference to http://hl7.org/fhir/StructureDefinition/Patient. Absolute URLs are only allowed for logical models (and can only be used in references in logical models, not resources).

This element is used to indicate the type of the target of the reference. This may be used which ever of the other elements are populated (or not). In some cases, the type of the target may be determined by inspection of the reference (e.g. a known RESTful URL) or by resolving the target of the reference.

Unless not suitable, these codes SHALL be taken from ResourceType
(extensible to http://hl7.org/fhir/ValueSet/resource-types|5.0.0)

Aa resource (or, for logical models, the URI of the logical model).

An identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

When an identifier is provided in place of a reference, any system processing the reference will only be able to resolve the identifier to a reference if it understands the business context in which the identifier is used. Sometimes this is global (e.g. a national identifier) but often it is not. For this reason, none of the useful mechanisms described for working with references (e.g. chaining, includes) are possible, nor should servers be expected to be able resolve the reference. Servers may accept an identifier based reference untouched, resolve it, and/or reject it - see CapabilityStatement.rest.resource.referencePolicy.

When both an identifier and a literal reference are provided, the literal reference is preferred. Applications processing the resource are allowed - but not required - to check that the identifier matches the literal reference

Applications converting a logical reference to a literal reference may choose to leave the logical reference present, or remove it.

Reference is intended to point to a structure that can potentially be expressed as a FHIR resource, though there is no need for it to exist as an actual FHIR resource instance - except in as much as an application wishes to actual find the target of the reference. The content referred to be the identifier must meet the logical constraints implied by any limitations on what resource types are permitted for the reference. For example, it would not be legitimate to send the identifier for a drug prescription if the type were Reference(Observation|DiagnosticReport). One of the use-cases for Reference.identifier is the situation where no FHIR representation exists (where the type is Reference (Any).

This element only allows for a single identifier. In the case where additional identifers are required, use the http://hl7.org/fhir/StructureDefinition/additionalIdentifier extension.

Plain text narrative that identifies the resource in addition to the resource reference.

This is generally not the same as the Resource.text of the referenced resource. The purpose is to identify what's being referenced, not to fully describe it.

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

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

Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.

An Extension

STU3: Group.member.period additional types (Period) additional types from child elements (end, start)

Element Group.member.period is mapped to FHIR R5 element Group.member.period as SourceIsBroaderThanTarget. The mappings for Group.member.period do not cover the following types: Period. The mappings for Group.member.period do not cover the following types based on type expansion: end, start.

The start of the period. The boundary is inclusive.

If the low element is missing, the meaning is that the low boundary is not known.

The end of the period. If the end of the period is missing, it means no end was known or planned at the time the instance was created. The start may be in the past, and the end date in the future, which means that period is expected/planned to end at that time.

The end value includes any matching date/time. i.e. 2012-02-03T10:00:00 is in a period that has an end value of 2012-02-03.

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

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