This page is part of the FHIR Specification (v5.0.0-snapshot3: R5 Snapshot #3, to support Connectathon 32). The current version which supercedes this version is 5.0.0. For a full list of available versions, see the Directory of published versions . Page versions: R5 R4B R4 R3

5.7 Resource CompartmentDefinition - Content

FHIR Infrastructure icon

Work Group

Maturity Level: 1

Trial Use

Security Category: Anonymous

Compartments: Not linked to any defined compartments

A compartment definition that defines how resources are accessed on a server.

5.7.1 Scope and Usage

Each resource may belong to one or more logical compartments. A compartment is a logical grouping of resources which share a common property. Compartments have two principal roles:

Function as an access mechanism for finding a set of related resources quickly
Provide a definitional basis for applying access control to resources quickly

Notes:

At present, compartment definitions can only be defined by HL7 International. This is because their existence creates significant impact on the behavior of servers.
Although compartment definitions can be a useful foundation for access control, they may not be sufficient for this purpose. Resources outside the compartment might still be appropriate to be made available or subject to compartment restrictions even though they are not formally part of the compartment (see below about access rules).

5.7.2 Boundaries and Relationships

Compartment definitions describe how particular compartment instances are named and identified, and how systems know which resources are in the compartment. The following compartments are defined by this specification:

Title

Description

Identity

Membership

Patient

The set of resources associated with a particular patient

There is an instance of the patient compartment for each patient resource, and the identity of the compartment is the same as the patient. When a patient is linked to another patient resource, the records associated with the linked patient resource will not be returned as part of the compartment search. Those records will be returned only with another compartment search using the "id" for the linked patient resource. In cases where two patients have been merged rather than linked, associated resources should be moved to the target patient as part of the merge process, so the patient compartment for the target patient would include all relevant data, and the patient compartment for the source patient would include only the linked Patient and possibly remnant resources like AuditEvent.

The patient compartment includes any resources where the subject of the resource is the patient, and some other resources that are directly linked to resources in the patient compartment

Encounter

The set of resources associated with a particular encounter

There is an instance of the encounter compartment for each encounter resource, and the identity of the compartment is the same as the encounter

The encounter compartment includes any resources where the resource has an explicitly nominated encounter, and some other resources that themselves link to resources in the encounter compartment. Note that for many resources, the exact nature of the link to encounter can be ambiguous (e.g. for a DiagnosticReport, is it the encounter when it was initiated, or when it was reported?)

RelatedPerson

The set of resources associated with a particular 'related person'

There is an instance of the relatedPerson compartment for each relatedPerson resource, and the identity of the compartment is the same as the relatedPerson

The relatedPerson compartment includes any resources where the resource is explicitly linked to relatedPerson (usually as author)

Practitioner

The set of resources associated with a particular practitioner

There is an instance of the practitioner compartment for each Practitioner resource, and the identity of the compartment is the same as the Practitioner

The practitioner compartment includes any resources where the resource is explicitly linked to a Practitioner (usually as author, but other kinds of linkage exist)

Device

The set of resources associated with a particular device

There is an instance of the device compartment for each Device resource, and the identity of the compartment is the same as the Device

The device compartment includes any resources where the resource is explicitly linked to a Device (mostly subject or performer)

The full definitions of these compartments are published as CompartmentDefinition resources. Servers typically do not support the full definition of a compartment, and are not required to. Systems may publish CompartmentDefinition resources so that other systems may make use of compartments properly.

CompartmentDefinitions are used by CapabilityStatement instances for specifying how resources are accessed

GraphDefinition also provides a mechanism for grouping resources, though it does not provide an additional search mechanism. Inclusion of resources in a GraphDefinition supports more complex criteria for inclusion than that allowed by CompartmentDefinition.

5.7.3 References to this Resource

Resource References: CapabilityStatement

Structure

Name	Flags	Card.	Type	Description & Constraints
CompartmentDefinition	TU		DomainResource	Compartment Definition for a resource + Warning: Name should be usable as an identifier for the module by machine processing applications such as code generation Elements defined in Ancestors: id, meta, implicitRules, language, text, contained, extension, modifierExtension Interfaces Implemented: CanonicalResource
url	Σ C	1..1	uri	Canonical identifier for this compartment definition, represented as a URI (globally unique) + Warning: URL should not contain \| or # - these characters make processing canonical references problematic
version	Σ	0..1	string	Business version of the compartment definition
versionAlgorithm[x]	Σ	0..1		How to compare versions Version Algorithm (Extensible)
versionAlgorithmString			string
versionAlgorithmCoding			Coding
name	Σ C	1..1	string	Name for this compartment definition (computer friendly)
title	Σ T	0..1	string	Name for this compartment definition (human friendly)
status	?!Σ	1..1	code	draft \| active \| retired \| unknown PublicationStatus (Required)
experimental	Σ	0..1	boolean	For testing purposes, not real usage
date	Σ	0..1	dateTime	Date last changed
publisher	Σ T	0..1	string	Name of the publisher/steward (organization or individual)
contact	Σ	0..*	ContactDetail	Contact details for the publisher
description	T	0..1	markdown	Natural language description of the compartment definition
useContext	Σ	0..*	UsageContext	The context that the content is intended to support
purpose	T	0..1	markdown	Why this compartment definition is defined
code	Σ	1..1	code	Patient \| Encounter \| RelatedPerson \| Practitioner \| Device CompartmentType (Required)
search	Σ	1..1	boolean	Whether the search syntax is supported
resource	Σ	0..*	BackboneElement	How a resource is related to the compartment
code	Σ	1..1	code	Name of resource type Resource Types (Required)
param	Σ	0..*	string	Search Parameter Name, or chained parameters
documentation		0..1	string	Additional documentation about the resource and compartment
startParam		0..1	uri	Search Param for interpreting $everything.start
endParam		0..1	uri	Search Param for interpreting $everything.end
Documentation for this format

See the Extensions for this resource

UML Diagram (Legend)

XML Template

<CompartmentDefinition xmlns="http://hl7.org/fhir"> 
 <!-- from Resource: id, meta, implicitRules, and language -->
 <!-- from DomainResource: text, contained, extension, and modifierExtension -->
 <url value="[uri]"/><!-- 1..1 Canonical identifier for this compartment definition, represented as a URI (globally unique) -->
 <version value="[string]"/><!-- 0..1 Business version of the compartment definition -->
 <versionAlgorithm[x]><!-- 0..1 string|Coding How to compare versions --></versionAlgorithm[x]>
 <name value="[string]"/><!-- I 1..1 Name for this compartment definition (computer friendly) -->
 <title value="[string]"/><!-- 0..1 Name for this compartment definition (human friendly) -->
 <status value="[code]"/><!-- 1..1 draft | active | retired | unknown -->
 <experimental value="[boolean]"/><!-- 0..1 For testing purposes, not real usage -->
 <date value="[dateTime]"/><!-- 0..1 Date last changed -->
 <publisher value="[string]"/><!-- 0..1 Name of the publisher/steward (organization or individual) -->
 <contact><!-- 0..* ContactDetail Contact details for the publisher --></contact>
 <description value="[markdown]"/><!-- 0..1 Natural language description of the compartment definition -->
 <useContext><!-- 0..* UsageContext The context that the content is intended to support --></useContext>
 <purpose value="[markdown]"/><!-- 0..1 Why this compartment definition is defined -->
 <code value="[code]"/><!-- 1..1 Patient | Encounter | RelatedPerson | Practitioner | Device -->
 <search value="[boolean]"/><!-- 1..1 Whether the search syntax is supported -->
 <resource>  <!-- 0..* How a resource is related to the compartment -->
  <code value="[code]"/><!-- 1..1 Name of resource type -->
  <param value="[string]"/><!-- 0..* Search Parameter Name, or chained parameters -->
  <documentation value="[string]"/><!-- 0..1 Additional documentation about the resource and compartment -->
  <startParam value="[uri]"/><!-- 0..1 Search Param for interpreting $everything.start -->
  <endParam value="[uri]"/><!-- 0..1 Search Param for interpreting $everything.end -->
 </resource>
</CompartmentDefinition>

JSON Template

{
  "resourceType" : "CompartmentDefinition",
  // from Resource: id, meta, implicitRules, and language
  // from DomainResource: text, contained, extension, and modifierExtension
  "url" : "<uri>", // R!  Canonical identifier for this compartment definition, represented as a URI (globally unique)
  "version" : "<string>", // Business version of the compartment definition
  // versionAlgorithm[x]: How to compare versions. One of these 2:
  "versionAlgorithmString" : "<string>",
  "versionAlgorithmCoding" : { Coding },
  "name" : "<string>", // I R!  Name for this compartment definition (computer friendly)
  "title" : "<string>", // Name for this compartment definition (human friendly)
  "status" : "<code>", // R!  draft | active | retired | unknown
  "experimental" : <boolean>, // For testing purposes, not real usage
  "date" : "<dateTime>", // Date last changed
  "publisher" : "<string>", // Name of the publisher/steward (organization or individual)
  "contact" : [{ ContactDetail }], // Contact details for the publisher
  "description" : "<markdown>", // Natural language description of the compartment definition
  "useContext" : [{ UsageContext }], // The context that the content is intended to support
  "purpose" : "<markdown>", // Why this compartment definition is defined
  "code" : "<code>", // R!  Patient | Encounter | RelatedPerson | Practitioner | Device
  "search" : <boolean>, // R!  Whether the search syntax is supported
  "resource" : [{ // How a resource is related to the compartment
    "code" : "<code>", // R!  Name of resource type
    "param" : ["<string>"], // Search Parameter Name, or chained parameters
    "documentation" : "<string>", // Additional documentation about the resource and compartment
    "startParam" : "<uri>", // Search Param for interpreting $everything.start
    "endParam" : "<uri>" // Search Param for interpreting $everything.end
  }]
}

Turtle Template

@prefix fhir: <http://hl7.org/fhir/> .


[ a fhir:CompartmentDefinition;
  fhir:nodeRole fhir:treeRoot; # if this is the parser root

  # from Resource: .id, .meta, .implicitRules, and .language
  # from DomainResource: .text, .contained, .extension, and .modifierExtension
  fhir:CompartmentDefinition.url [ uri ]; # 1..1 Canonical identifier for this compartment definition, represented as a URI (globally unique)
  fhir:CompartmentDefinition.version [ string ]; # 0..1 Business version of the compartment definition
  # CompartmentDefinition.versionAlgorithm[x] : 0..1 How to compare versions. One of these 2
    fhir:CompartmentDefinition.versionAlgorithmString [ string ]
    fhir:CompartmentDefinition.versionAlgorithmCoding [ Coding ]
  fhir:CompartmentDefinition.name [ string ]; # 1..1 I Name for this compartment definition (computer friendly)
  fhir:CompartmentDefinition.title [ string ]; # 0..1 Name for this compartment definition (human friendly)
  fhir:CompartmentDefinition.status [ code ]; # 1..1 draft | active | retired | unknown
  fhir:CompartmentDefinition.experimental [ boolean ]; # 0..1 For testing purposes, not real usage
  fhir:CompartmentDefinition.date [ dateTime ]; # 0..1 Date last changed
  fhir:CompartmentDefinition.publisher [ string ]; # 0..1 Name of the publisher/steward (organization or individual)
  fhir:CompartmentDefinition.contact [ ContactDetail ], ... ; # 0..* Contact details for the publisher
  fhir:CompartmentDefinition.description [ markdown ]; # 0..1 Natural language description of the compartment definition
  fhir:CompartmentDefinition.useContext [ UsageContext ], ... ; # 0..* The context that the content is intended to support
  fhir:CompartmentDefinition.purpose [ markdown ]; # 0..1 Why this compartment definition is defined
  fhir:CompartmentDefinition.code [ code ]; # 1..1 Patient | Encounter | RelatedPerson | Practitioner | Device
  fhir:CompartmentDefinition.search [ boolean ]; # 1..1 Whether the search syntax is supported
  fhir:CompartmentDefinition.resource [ # 0..* How a resource is related to the compartment
    fhir:CompartmentDefinition.resource.code [ code ]; # 1..1 Name of resource type
    fhir:CompartmentDefinition.resource.param [ string ], ... ; # 0..* Search Parameter Name, or chained parameters
    fhir:CompartmentDefinition.resource.documentation [ string ]; # 0..1 Additional documentation about the resource and compartment
    fhir:CompartmentDefinition.resource.startParam [ uri ]; # 0..1 Search Param for interpreting $everything.start
    fhir:CompartmentDefinition.resource.endParam [ uri ]; # 0..1 Search Param for interpreting $everything.end
  ], ...;
]

Changes since R4

CompartmentDefinition

CompartmentDefinition.versionAlgorithm[x]

Added Element

CompartmentDefinition.title

Added Element

CompartmentDefinition.resource.startParam

Added Element

CompartmentDefinition.resource.endParam

Added Element

See the Full Difference for further information

This analysis is available as XML or JSON.

See R3 <--> R4 Conversion Maps (status = 6 tests that all execute ok. 1 fail round-trip testing and 5 r3 resources are invalid (0 errors).)

Structure

Name	Flags	Card.	Type	Description & Constraints
CompartmentDefinition	TU		DomainResource	Compartment Definition for a resource + Warning: Name should be usable as an identifier for the module by machine processing applications such as code generation Elements defined in Ancestors: id, meta, implicitRules, language, text, contained, extension, modifierExtension Interfaces Implemented: CanonicalResource
url	Σ C	1..1	uri	Canonical identifier for this compartment definition, represented as a URI (globally unique) + Warning: URL should not contain \| or # - these characters make processing canonical references problematic
version	Σ	0..1	string	Business version of the compartment definition
versionAlgorithm[x]	Σ	0..1		How to compare versions Version Algorithm (Extensible)
versionAlgorithmString			string
versionAlgorithmCoding			Coding
name	Σ C	1..1	string	Name for this compartment definition (computer friendly)
title	Σ T	0..1	string	Name for this compartment definition (human friendly)
status	?!Σ	1..1	code	draft \| active \| retired \| unknown PublicationStatus (Required)
experimental	Σ	0..1	boolean	For testing purposes, not real usage
date	Σ	0..1	dateTime	Date last changed
publisher	Σ T	0..1	string	Name of the publisher/steward (organization or individual)
contact	Σ	0..*	ContactDetail	Contact details for the publisher
description	T	0..1	markdown	Natural language description of the compartment definition
useContext	Σ	0..*	UsageContext	The context that the content is intended to support
purpose	T	0..1	markdown	Why this compartment definition is defined
code	Σ	1..1	code	Patient \| Encounter \| RelatedPerson \| Practitioner \| Device CompartmentType (Required)
search	Σ	1..1	boolean	Whether the search syntax is supported
resource	Σ	0..*	BackboneElement	How a resource is related to the compartment
code	Σ	1..1	code	Name of resource type Resource Types (Required)
param	Σ	0..*	string	Search Parameter Name, or chained parameters
documentation		0..1	string	Additional documentation about the resource and compartment
startParam		0..1	uri	Search Param for interpreting $everything.start
endParam		0..1	uri	Search Param for interpreting $everything.end
Documentation for this format

See the Extensions for this resource

UML Diagram (Legend)

XML Template

<CompartmentDefinition xmlns="http://hl7.org/fhir"> 
 <!-- from Resource: id, meta, implicitRules, and language -->
 <!-- from DomainResource: text, contained, extension, and modifierExtension -->
 <url value="[uri]"/><!-- 1..1 Canonical identifier for this compartment definition, represented as a URI (globally unique) -->
 <version value="[string]"/><!-- 0..1 Business version of the compartment definition -->
 <versionAlgorithm[x]><!-- 0..1 string|Coding How to compare versions --></versionAlgorithm[x]>
 <name value="[string]"/><!-- I 1..1 Name for this compartment definition (computer friendly) -->
 <title value="[string]"/><!-- 0..1 Name for this compartment definition (human friendly) -->
 <status value="[code]"/><!-- 1..1 draft | active | retired | unknown -->
 <experimental value="[boolean]"/><!-- 0..1 For testing purposes, not real usage -->
 <date value="[dateTime]"/><!-- 0..1 Date last changed -->
 <publisher value="[string]"/><!-- 0..1 Name of the publisher/steward (organization or individual) -->
 <contact><!-- 0..* ContactDetail Contact details for the publisher --></contact>
 <description value="[markdown]"/><!-- 0..1 Natural language description of the compartment definition -->
 <useContext><!-- 0..* UsageContext The context that the content is intended to support --></useContext>
 <purpose value="[markdown]"/><!-- 0..1 Why this compartment definition is defined -->
 <code value="[code]"/><!-- 1..1 Patient | Encounter | RelatedPerson | Practitioner | Device -->
 <search value="[boolean]"/><!-- 1..1 Whether the search syntax is supported -->
 <resource>  <!-- 0..* How a resource is related to the compartment -->
  <code value="[code]"/><!-- 1..1 Name of resource type -->
  <param value="[string]"/><!-- 0..* Search Parameter Name, or chained parameters -->
  <documentation value="[string]"/><!-- 0..1 Additional documentation about the resource and compartment -->
  <startParam value="[uri]"/><!-- 0..1 Search Param for interpreting $everything.start -->
  <endParam value="[uri]"/><!-- 0..1 Search Param for interpreting $everything.end -->
 </resource>
</CompartmentDefinition>

JSON Template

{
  "resourceType" : "CompartmentDefinition",
  // from Resource: id, meta, implicitRules, and language
  // from DomainResource: text, contained, extension, and modifierExtension
  "url" : "<uri>", // R!  Canonical identifier for this compartment definition, represented as a URI (globally unique)
  "version" : "<string>", // Business version of the compartment definition
  // versionAlgorithm[x]: How to compare versions. One of these 2:
  "versionAlgorithmString" : "<string>",
  "versionAlgorithmCoding" : { Coding },
  "name" : "<string>", // I R!  Name for this compartment definition (computer friendly)
  "title" : "<string>", // Name for this compartment definition (human friendly)
  "status" : "<code>", // R!  draft | active | retired | unknown
  "experimental" : <boolean>, // For testing purposes, not real usage
  "date" : "<dateTime>", // Date last changed
  "publisher" : "<string>", // Name of the publisher/steward (organization or individual)
  "contact" : [{ ContactDetail }], // Contact details for the publisher
  "description" : "<markdown>", // Natural language description of the compartment definition
  "useContext" : [{ UsageContext }], // The context that the content is intended to support
  "purpose" : "<markdown>", // Why this compartment definition is defined
  "code" : "<code>", // R!  Patient | Encounter | RelatedPerson | Practitioner | Device
  "search" : <boolean>, // R!  Whether the search syntax is supported
  "resource" : [{ // How a resource is related to the compartment
    "code" : "<code>", // R!  Name of resource type
    "param" : ["<string>"], // Search Parameter Name, or chained parameters
    "documentation" : "<string>", // Additional documentation about the resource and compartment
    "startParam" : "<uri>", // Search Param for interpreting $everything.start
    "endParam" : "<uri>" // Search Param for interpreting $everything.end
  }]
}

Turtle Template

@prefix fhir: <http://hl7.org/fhir/> .


[ a fhir:CompartmentDefinition;
  fhir:nodeRole fhir:treeRoot; # if this is the parser root

  # from Resource: .id, .meta, .implicitRules, and .language
  # from DomainResource: .text, .contained, .extension, and .modifierExtension
  fhir:CompartmentDefinition.url [ uri ]; # 1..1 Canonical identifier for this compartment definition, represented as a URI (globally unique)
  fhir:CompartmentDefinition.version [ string ]; # 0..1 Business version of the compartment definition
  # CompartmentDefinition.versionAlgorithm[x] : 0..1 How to compare versions. One of these 2
    fhir:CompartmentDefinition.versionAlgorithmString [ string ]
    fhir:CompartmentDefinition.versionAlgorithmCoding [ Coding ]
  fhir:CompartmentDefinition.name [ string ]; # 1..1 I Name for this compartment definition (computer friendly)
  fhir:CompartmentDefinition.title [ string ]; # 0..1 Name for this compartment definition (human friendly)
  fhir:CompartmentDefinition.status [ code ]; # 1..1 draft | active | retired | unknown
  fhir:CompartmentDefinition.experimental [ boolean ]; # 0..1 For testing purposes, not real usage
  fhir:CompartmentDefinition.date [ dateTime ]; # 0..1 Date last changed
  fhir:CompartmentDefinition.publisher [ string ]; # 0..1 Name of the publisher/steward (organization or individual)
  fhir:CompartmentDefinition.contact [ ContactDetail ], ... ; # 0..* Contact details for the publisher
  fhir:CompartmentDefinition.description [ markdown ]; # 0..1 Natural language description of the compartment definition
  fhir:CompartmentDefinition.useContext [ UsageContext ], ... ; # 0..* The context that the content is intended to support
  fhir:CompartmentDefinition.purpose [ markdown ]; # 0..1 Why this compartment definition is defined
  fhir:CompartmentDefinition.code [ code ]; # 1..1 Patient | Encounter | RelatedPerson | Practitioner | Device
  fhir:CompartmentDefinition.search [ boolean ]; # 1..1 Whether the search syntax is supported
  fhir:CompartmentDefinition.resource [ # 0..* How a resource is related to the compartment
    fhir:CompartmentDefinition.resource.code [ code ]; # 1..1 Name of resource type
    fhir:CompartmentDefinition.resource.param [ string ], ... ; # 0..* Search Parameter Name, or chained parameters
    fhir:CompartmentDefinition.resource.documentation [ string ]; # 0..1 Additional documentation about the resource and compartment
    fhir:CompartmentDefinition.resource.startParam [ uri ]; # 0..1 Search Param for interpreting $everything.start
    fhir:CompartmentDefinition.resource.endParam [ uri ]; # 0..1 Search Param for interpreting $everything.end
  ], ...;
]

Changes since Release 4

CompartmentDefinition

CompartmentDefinition.versionAlgorithm[x]

Added Element

CompartmentDefinition.title

Added Element

CompartmentDefinition.resource.startParam

Added Element

CompartmentDefinition.resource.endParam

Added Element

See the Full Difference for further information

This analysis is available as XML or JSON.

See R3 <--> R4 Conversion Maps (status = 6 tests that all execute ok. 1 fail round-trip testing and 5 r3 resources are invalid (0 errors).)

Additional definitions: Master Definition XML + JSON, XML Schema/Schematron + JSON Schema, ShEx (for Turtle) , the spreadsheet version & the dependency analysis

5.7.4.1 Terminology Bindings

Path	Definition	Type	Reference
CompartmentDefinition.versionAlgorithm[x]	Indicates the mechanism used to compare versions to determine which is more current.	Extensible	VersionAlgorithm
CompartmentDefinition.status	The lifecycle status of an artifact.	Required	PublicationStatus
CompartmentDefinition.code	Which type a compartment definition describes.	Required	CompartmentType
CompartmentDefinition.resource.code	All fhir data types	Required	ResourceType

Path

Definition

Type

Reference

CompartmentDefinition.versionAlgorithm[x]

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

Extensible

VersionAlgorithm

CompartmentDefinition.status

The lifecycle status of an artifact.

Required

PublicationStatus

CompartmentDefinition.code

Which type a compartment definition describes.

Required

CompartmentType

CompartmentDefinition.resource.code

All fhir data types

Required

ResourceType

5.7.4.2 Constraints

UniqueKey

Level

Location

Description

Expression

cnl-0

Warning

(base)

Name should be usable as an identifier for the module by machine processing applications such as code generation

name.exists() implies name.matches('[A-Z]([A-Za-z0-9_]){1,254}')

cnl-1

Warning

CompartmentDefinition.url

URL should not contain | or # - these characters make processing canonical references problematic

url.matches('([^|#])*')

5.7.4.3 Base Resource

A compartment implicitly always includes the resource that is a 'root' of the compartment e.g. the resource Patient/123 is the root resource of the Patient Compartment for Patient/123. Thus an operation that retrieves everything within the compartment will include the base resource; a scope that grants access to everything within the compartment will grant access to the resource; etc.

5.7.4.4 Using Compartments

As an example of compartment usage, to retrieve a list of a patient's conditions, use the URL:

  GET [base]/Patient/[id]/Condition

Additional search parameters can be defined, such as this hypothetical search for acute conditions:

  GET [base]/Patient/[id]/Condition?code:in=http://hspc.org/ValueSet/acute-concerns

Note that as searches, these are syntactic variations on these two search URLs respectively:

  GET [base]/Condition?patient=[id]
  GET [base]/Condition?patient=[id]&code:in=http://hspc.org/ValueSet/acute-concerns

The outcome of a compartment search is the same as the equivalent normal search. For example, both these searches return the same outcome if there is no patient 333:

  GET [base]/Patient/333/Condition
  GET [base]/Condition?patient=333

Whether the patient doesn't exist, or the user has no access to the patient, both these searches return an empty bundle with no matches. Some systems will include an operation outcome warning that there is no matching patient.

However, there is a key difference in functionality between compartment based searches and direct searches with parameters. Consider this search:

  GET [base]/Patient/[id]/Communication

Because the definition of the patient compartment for Communication says that a Communication resource is in the patient compartment if the subject, sender, or recipient is the patient, the compartment search is actually the same as the union of these 3 searches:

  GET [base]/Communication?subject=[id]
  GET [base]/Communication?sender=[id]
  GET [base]/Communication?recipient=[id]

There is no way to do this as a single search, except by using the _filter:

  GET [base]/Communication?_filter=subject re [id] or sender re [id] or recipient re [id]

Further details of searching by compartment are described under the search operation. As a search related operation, the assignment of resources to compartments is only based on the current version of any of the resources involved. Note that contained patient resources cannot create a patient compartment of their own.

Note that while this specification describes how to use the compartment syntax to find resources that are logically associated with the compartment, the compartment is not part of the identity of the resource. E.g. the response to the following is not defined by this specification:

  GET [base]/Patient/[patient-id]/Condition/[resource-id]

The response for write operations (PUT/DELETE/PATCH) are also not defined by this specification. Nor is the response to a POST defined:

  POST [base]/Patient/[patient-id]/Condition

There is no expectation for servers to support either read or write to such URLs.

5.7.4.5 Logical Meaning of Compartments

Compartments may be used explicitly, like this, but can also be used implicitly. For instance, if a FHIR server is providing a patient view of a record, the authorized user associated with use of the FHIR RESTful API may be limited to accessing records from the compartment instance(s) logically associated with their identity. Irrespective of whether compartments are being used explicitly or implicitly, servers will need to make arrangements to make some resources with no direct link to a patient available to the client (medications, substances, binaries, etc.).

Note that resources may cross between compartments, or interlink them. Examples of this would be where a Diagnostic Report identifies a subject, but an Observation it references identifies a different subject, or where a List resource references items that identify different subjects. Such cross-linking may arise for many valid reasons, including:

Cases where subject records are inter-linked - Transplants, Perinatal care, family therapy etc.
Workflow management where action lists link multiple patients and/or practitioners

Given the wide variety of use cases and contexts in which FHIR is used, compartments do not define how cross-linking is handled. Systems may reject resources, remove them from both compartments, or place them in both, or act in some other fashion.

The graph definition resource provides a method by which rules about cross-linking may be made and enforced.

It is at the discretion of the server whether to include resources in a compartment when the reference to the resource that establishes the compartment is in an extension.

Some resources are not in any compartment, e.g. Medication, Substance, Location. These resources are not linked directly to a patient or authored record, and are sometimes called 'master files'. Servers will need to make arrangements to make these resources available to the clients that are limited to particular compartments. For example, a Medication resource describes a medication itself and does not link to a patient; however, a resource such as MedicationAdministration connects the Medication (details of what was administered) to the patient (for whom was it administered), and so is required to interpret the administration.

5.7.5 Defining New Compartments

Compartments are defined and added to the list above when implementer communities identify them as common access points for data. As described below, compartments have both syntactical and logical consequences, and both these aspects of their functionality are evaluated when deciding whether to define compartments.

5.7.6 Search Parameters

Search parameters for this resource. The common parameters also apply. See Searching for more information about searching in REST, messaging, and services.

Name	Type	Description	Expression	In Common
code	token	Patient \| Encounter \| RelatedPerson \| Practitioner \| Device	CompartmentDefinition.code
context	token	A use context assigned to the compartment definition	(CompartmentDefinition.useContext.value as CodeableConcept)	30 Resources
context-quantity	quantity	A quantity- or range-valued use context assigned to the compartment definition	(CompartmentDefinition.useContext.value as Quantity) \| (CompartmentDefinition.useContext.value as Range)	30 Resources
context-type	token	A type of use context assigned to the compartment definition	CompartmentDefinition.useContext.code	30 Resources
context-type-quantity	composite	A use context type and quantity- or range-based value assigned to the compartment definition	On CompartmentDefinition.useContext: context-type: code context-quantity: value.ofType(Quantity) \| value.ofType(Range)	30 Resources
context-type-value	composite	A use context type and value assigned to the compartment definition	On CompartmentDefinition.useContext: context-type: code context: value.ofType(CodeableConcept)	30 Resources
date	date	The compartment definition publication date	CompartmentDefinition.date	30 Resources
description	string	The description of the compartment definition	CompartmentDefinition.description	28 Resources
name	string	Computationally friendly name of the compartment definition	CompartmentDefinition.name	26 Resources
publisher	string	Name of the publisher of the compartment definition	CompartmentDefinition.publisher	30 Resources
resource	token	Name of resource type	CompartmentDefinition.resource.code
status	token	The current status of the compartment definition	CompartmentDefinition.status	34 Resources
url	uri	The uri that identifies the compartment definition	CompartmentDefinition.url	33 Resources
version	token	The business version of the compartment definition	CompartmentDefinition.version	30 Resources