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 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.

Specifies the package in which an artifact is or was included.

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 it's narrative along with other profiles, value sets, etc.

An Extension

A reference to a Library containing the formal logic used by the artifact.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

An expression that defines the criteria for group membership. This extension can only be used on a Group resource with a membership of definitional. When this expression is used, the Group resource cannot have any characteristic elements; this mechanism is exclusive with characteristics. The result of the expression SHALL be boolean-valued. The expression SHALL be parameterized with a %context variable that represents the subject being tested for membership. If evaluation of the expression results in true, the subject is considered a member of the group.

Defines a knowledge capability afforded by this knowledge artifact.

The date (and optionally time) when the artifact 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 artifact changes.

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 artifact. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource.

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

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

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 artifact instances.

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

A legal or geographic region in which the authority that maintains the resource is operating.

It may be possible for the artifact to be used in jurisdictions other than those for which it was originally designed or intended - that would be in Artifact use context.

Explanation of why this artifact is needed and why it has been designed as it has.

This element does not describe the usage of the artifact. 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 artifact.

A detailed description of how the artifact is used from a clinical perspective.

A copyright statement relating to the artifact and/or its contents. Copyright statements are generally legal restrictions on the use and publishing of the artifact.

The short copyright declaration (e.g. (c) '2015+ xyz organization' should be sent in the copyrightLabel element.

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

Defines the content expected to be rendered in all representations of the artifact. The (c) symbol should NOT be included in this string. It is expected to be added by software when rendering the notation. Full details about licensing, restrictions, warrantees, etc. goes in the more general 'copyright' element.

The date on which the artifact content was approved by the publisher. Approval happens once when the content is officially approved for usage.

The 'date' element may be more recent than the approval date because of minor changes or editorial corrections.

The date on which the resource content was last reviewed. Review happens periodically after approval but does not change the original approval date.

If specified, this date follows the original approval date.

The period during which the artifact content was or is planned to be in active use.

The effective period for an artifact determines when the content is applicable for usage and is independent of publication and review dates. For example, an artifact intended to be used for the year 2016 might be published in 2015.

Descriptive topics related to the content of the artifact. Topics provide a high-level categorization of the artifact that can be useful for filtering and searching.

This element provides a topical categorization of the artifact, as opposed to the more structured context-of-use information provided in the useContext element.

An individual or organization primarily involved in the creation and maintenance of the artifact.

An individual or organization primarily responsible for internal coherence of the artifact.

An individual or organization primarily responsible for review of some aspect of the artifact.

An individual or organization responsible for officially endorsing the artifact for use in some setting.

Related artifacts such as additional documentation, justification, dependencies, bibliographic references, and predecessor and successor artifacts.

Each related artifact is either an attachment, or a reference to another resource, but not both.

An Extension

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

Specifies the publication date of the referenced artifacts.

Specifies the publication status of the referenced artifacts.

The type of relationship to the related artifact.

The type of relationship to the related artifact.

A reference to the offical/source of truth definition of the content, typically outside the FHIR ecosystem. For example, the authoritativeSource for a ValueSet might be a spreadsheet published on an agency website.

Note that this concept is different from web-source (where the page for the content can be found it is different from the canonical), and package-source (what package the resource came from). This is an abbreviated way of saying something that could be expressed with Provenance. This extensions points to the content, not the authority for the content.

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 manageable, 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.

A unique business identifier for this group.

Allows the group to be referenced from external specifications.

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, Device, Medication or Substance for the other types.).

Types of resources that are part of group.

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

If true, indicates that the resource refers to a specific group of real individuals. If false, the group defines a set of intended individuals.

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 flag.

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.

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.

A reference to a resource, canonical resource, or non-FHIR resource.

An Extension

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

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.

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 manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. 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.

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.

The value of the characteristic is what determines group membership.

Instances that conform to the referenced profile are included (or excluded if characteristic.exclude is true) in the cohort.

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.

Identifies the resource instances that are members of the group.

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

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 manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension. 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.

A reference to a resource, canonical resource, or non-FHIR resource.

An Extension

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

Create a reference, following canonical reference semantics, to an artifact that uses the artifact-url and artifact-version extensions to provide a canonical identifier.

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.

The only time that a resource does not have an id is when it is being submitted to the server using a create operation.

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.

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

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.

Specifies the package in which an artifact is or was included.

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 value is always populated except when the resource is first being created. 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.

In the provenance resource, this corresponds to Provenance.entity.what[x]. The exact use of the source (and the implied Provenance.entity.role) is left to implementer discretion. Only one nominated source is allowed; for additional provenance details, a full Provenance resource should be used.

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.

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 it's 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).

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 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.

These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope.

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

A reference to a Library containing the formal logic used by the artifact.

For questionnaires, see additional guidance and examples in the SDC implementation guide.

An expression that defines the criteria for group membership. This extension can only be used on a Group resource with a membership of definitional. When this expression is used, the Group resource cannot have any characteristic elements; this mechanism is exclusive with characteristics. The result of the expression SHALL be boolean-valued. The expression SHALL be parameterized with a %context variable that represents the subject being tested for membership. If evaluation of the expression results in true, the subject is considered a member of the group.

Defines a knowledge capability afforded by this knowledge artifact.

The date (and optionally time) when the artifact 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 artifact changes.

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 artifact. Additional specific dates may be added as extensions or be found by consulting Provenances associated with past versions of the resource.

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

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

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 artifact instances.

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

A legal or geographic region in which the authority that maintains the resource is operating.

It may be possible for the artifact to be used in jurisdictions other than those for which it was originally designed or intended - that would be in Artifact use context.

Explanation of why this artifact is needed and why it has been designed as it has.

This element does not describe the usage of the artifact. 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 artifact.

A detailed description of how the artifact is used from a clinical perspective.

A copyright statement relating to the artifact and/or its contents. Copyright statements are generally legal restrictions on the use and publishing of the artifact.

The short copyright declaration (e.g. (c) '2015+ xyz organization' should be sent in the copyrightLabel element.

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

Defines the content expected to be rendered in all representations of the artifact. The (c) symbol should NOT be included in this string. It is expected to be added by software when rendering the notation. Full details about licensing, restrictions, warrantees, etc. goes in the more general 'copyright' element.

The date on which the artifact content was approved by the publisher. Approval happens once when the content is officially approved for usage.

The 'date' element may be more recent than the approval date because of minor changes or editorial corrections.

The date on which the resource content was last reviewed. Review happens periodically after approval but does not change the original approval date.

If specified, this date follows the original approval date.

The period during which the artifact content was or is planned to be in active use.

The effective period for an artifact determines when the content is applicable for usage and is independent of publication and review dates. For example, an artifact intended to be used for the year 2016 might be published in 2015.

Descriptive topics related to the content of the artifact. Topics provide a high-level categorization of the artifact that can be useful for filtering and searching.

This element provides a topical categorization of the artifact, as opposed to the more structured context-of-use information provided in the useContext element.

An individual or organization primarily involved in the creation and maintenance of the artifact.

An individual or organization primarily responsible for internal coherence of the artifact.

An individual or organization primarily responsible for review of some aspect of the artifact.

An individual or organization responsible for officially endorsing the artifact for use in some setting.

Related artifacts such as additional documentation, justification, dependencies, bibliographic references, and predecessor and successor artifacts.

Each related artifact is either an attachment, or a reference to another resource, but not both.

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

An Extension

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

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 manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

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.

Specifies the publication date of the referenced artifacts.

Specifies the publication status of the referenced artifacts.

The type of relationship to the related artifact.

The type of relationship to the related artifact.

A short label that can be used to reference the citation from elsewhere in the containing artifact, such as a footnote index.

A brief description of the document or knowledge resource being referenced, suitable for display to a consumer.

A bibliographic citation for the related artifact. This text SHOULD be formatted according to an accepted citation format.

Additional structured information about citations should be captured as extensions.

A url for the artifact that can be followed to access the actual content.

If a document or resource element is present, this element SHALL NOT be provided (use the url or reference in the Attachment or resource reference).

The document being referenced, represented as an attachment. This is exclusive with the resource element.

The related resource, such as a library, value set, profile, or other knowledge resource.

If the type is predecessor, this is a reference to the succeeding knowledge resource. If the type is successor, this is a reference to the prior knowledge resource.

A reference to the offical/source of truth definition of the content, typically outside the FHIR ecosystem. For example, the authoritativeSource for a ValueSet might be a spreadsheet published on an agency website.

Note that this concept is different from web-source (where the page for the content can be found it is different from the canonical), and package-source (what package the resource came from). This is an abbreviated way of saying something that could be expressed with Provenance. This extensions points to the content, not the authority for the content.

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 manageable, 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.

A unique business identifier for this group.

Allows the group to be referenced from external specifications.

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, Device, Medication or Substance for the other types.).

Types of resources that are part of group.

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

If true, indicates that the resource refers to a specific group of real individuals. If false, the group defines a set of intended individuals.

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 flag.

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.

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.

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 manageable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.

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.

A reference to a resource, canonical resource, or non-FHIR 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

Source of the definition for the extension code - a logical name or a URL.

The definition may point directly to a computable or human-readable definition of the extensibility codes, or it may be a logical URI as declared in some other specification. The definition SHALL be a URI for the Structure Definition defining the extension.

Value of extension - must be one of a constrained set of the data types (see Extensibility for a list).

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.