Canonical Resource Management Infrastructure Implementation Guide
1.0.0 - STU1

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## Artifact Terminology Service

This page describes and documents the use cases and conformance expectations of a terminology service to support authoring, distribution, and evaluation of FHIR-based knowledge artifact specifications as described in this implementation guide.

This implementation guide is not advocating for any particular central authority for terminology content, rather the intent is to propose a capability statement that enables publishers to build consistent and interoperable terminology services that support authoring, distribution, and implementation of FHIR-based knowledge artifacts.

This implementation guide is not prescriptive about authentication or authorization, but strongly recommends that these capabilities be addressed through standard mechanisms, as described in FHIR standard security mechanisms. In addition, though knowledge artifacts typically do not include patient-specific information, test data for knowledge artifacts can sometimes be derived from or based on real patient information. In this cases, care must be taken to ensure the data is scrubbed to remove any possibility of violating patient privacy or security.

### Use Cases

Beyond the basic required use cases of searching, retrieving, and expanding value sets, applications that reference value sets that are defined in terms of code systems from different authorities and with different publishing timelines face common challenges related to stable expansion of those value sets. To address that general problem, this implementation guide proposes to use the Library resource as an artifact collection. Artifact collections are libraries of knowledge artifacts used to package sets of artifacts for development and release. From the perspective of a terminology service, artifact collections provide two main capabilities:

1. They act as a version manifest to specify the versions of dependencies used by artifacts in the collection
2. They allow expansion rules to be specified for value sets used by artifacts in the collection

Note that during the authoring phase, the value sets referenced by artifacts will change, but once released, the set is stable. Throughout this process, the focus of the capabilities supported by this service description are intended to ensure stable expansion of the value sets referenced by the artifacts.

#### Version Manifest

As a version manifest, an artifact collection specifies versioned canonical references for dependencies using `relatedArtifact` elements with a type of `depends-on`. Some systems will not support the ability to version manifests, any changes needed would require a new manifest. (i.e. versioning of manifests is a MAY)

> NOTE: If the version of an artifact is specified explicitly as part of the declaration in the artifact, the manifest approach cannot be used to override that version. For example, if an artifact explicitly references the version of a value set, the manifest cannot override that version.

#### Expansion Rules

Artifact collections can specify expansion rules for value sets referenced by artifacts in the collection. This is done using the cqf-expansionParameters extension to reference a contained Parameters resource, where the parameter elements provide a default value for parameters to the $expand operation, consistent with the conformance requirements for the $expand operation supported by an artifact terminology service, including support for the following parameters:

1. `activeOnly`
2. `system-version` (or `canonical-version`)
3. `check-system-version` (or `check-canonical-version`)
4. `force-system-version` (or `force-canonical-version`)
5. `expansion` parameter (defined in the crmi-valueset-expand)
6. `includeDraft` parameter (defined in the crmi-valueset-expand)

Because this capability results in the potential for parameter values to be supplied in multiple places, the following rules apply:

1. If a parameter is specified as part of the $expand operation directly, it takes precedence
2. If a ValueSet dependency is specified as part of the version manifest (and no version for the value set is specified in the artifact reference), the version has the same meaning as the `valueSetVersion` parameter to the $expand
3. If a CodeSystem dependency is specified as part of the version manifest (and no version for the code system is specified in the artifact reference), the version has the same meaning as the `system-version` parameter to the $expand
4. Version information specified in the expansion parameters takes precedence over version information specified as part of the version manifest (i.e. as a relatedArtifact dependency in the artifact collection library)

> NOTE: The term artifact collection can also be understood as a content Implementation Guide, in which case the ImplementationGuide resource serves as the container for the collection of artifacts; all the same discussions and use cases apply, in particular the ability to use the cqf-expansionParameters extension as described here. The CRMIImplementationGuide profile supports this use case.

For ImplementationGuide, this extension specifies expansion parameters to be used for all ValueSet expansions for ValueSets defined in the IG or referenced by artifacts defined in the IG.

Expansion parameters specified in the IG would override expansion parameters specified in dependency IGs, and can be overridden by expansion parameters in downstream IGs.

When the cqf-expansionParameters extension is used, it is intended to be binding (i.e. expansion SHALL take the expansion parameters into account, according to the expansion rules discussed here.

#### Hosted Content

Terminology services MAY act as a repository for content that is managed and created elsewhere (i.e. hosted content AKA a convenience copy), or they MAY provide features to author and manage content directly, or any combination. When hosting content that is managed elsewhere, the service must ensure that the content of the resource is materially the same (i.e. the values for all elements are the same where those elements are specified in the Shareable and Publishable profiles) as the source of truth. In particular, for systems that provide both management and hosting of externally managed content, the status element for hosted content SHALL be the same as the status of the content in the source of truth.

### Code Systems

1. SHALL Represent basic CodeSystem information, as specified by the ShareableCodeSystem profile, which includes url, version, name, status, experimental, publisher, description, caseSensitive, content, and concept.

2. For published CodeSystems, SHALL represent publishable CodeSystem information, as specified by the CRMIPublishableCodeSystem profile.

3. For hosted content, the data-absent-reason extension with a value of unknown MAY be used to satisfy required cardinality constraints of the Shareable and Publishable code system profiles when an element is not present in the source of truth for the content.

4. CodeSystem resources returned by the repository SHALL use the meta.profile element to indicate which profiles the CodeSystem resource conforms to.

5. SHALL support CodeSystem read by the server-defined id for the CodeSystem

6. SHALL support CodeSystem searches by:
   1. url: Returning all versions of the codesystem matching that url
   2. version: Returning the codesystem matching that version (can appear only in combination with a url search)
   3. identifier: Returning any codesystem matching the identifier
   4. name: Returning any codesystem matching the name, according to the string-matching semantics in FHIR
   5. title: Returning any codesystem matching the title, according to the string-matching semantics in FHIR
   6. description: Returning any codesystem matching the search description, according to string-matching semantics in FHIR
   7. code: Returning any codesystem with the given code
7. SHOULD support CodeSystem searches by:
   1. status: Returning codesystems that match the given status
   2. valueset: Returning any codesystem that is referenced by the given value set url (optionally versioned)
   3. library: Returning any codesystem that is referenced by the given library url (optionally versioned)
   4. artifact: Returning any codesystem that is referenced by the given artifact url (optionally versioned)

8. SHALL support CodeSystem/$lookup

9. SHALL support CodeSystem/$validate-code

When determining the URI for a code system, the HL7 Universal Terminology Governance (UTG) site is the source of truth. If a code system is not identified there, submit a request with the HL7 Terminology Authority to identify an appropriate URL. For example, HCPCS Level II codes are not specified yet, discussion can be found here.

In accordance with the FHIR specification, CodeSystem resources, and references to code systems SHALL use the URI as specified by the HL7 terminology authority. In addition, version identifiers for code systems are specified according to the rules identified by the code system authority. For example, for SNOMED-CT, this means the version string is required to specify the edition and the version:

    http://snomed.info/sct/731000124108/version/20150301

The edition identifier for the US Edition is `731000124108`, and the version in the above example is the March 2015 release, specified as YYYYMMDD, `20150301`.

Note that when a code system authority has not established a versioning system, terminology servers may, as a practical matter, determine an appropriate versioning system to enable consistent use of content from that code system. However, in this case, the selected versioning scheme SHALL be brought to the HL7 Terminology Authority for consideration as the standard versioning scheme for that code system.

### Value Sets

1. SHALL Represent basic ValueSet information, as specified by the ShareableValueSet profile, which includes url, version, name, status, experimental, publisher, and description.
   1. To support the ability to include specific codes that are inactive in their code systems, the following types of include elements SHALL be supported
      1. Concepts in a system (unspecified version)
      2. Concepts in a system (specified version)
      3. Value Sets

2. SHALL Represent computable ValueSet information, as specified by the CRMIComputableValueSet profile, which specifies the definition of a value set using established extensions, or with the `compose` element, including in particular the ability to use the `inactive` element of the `include` to indicate that a specific code is inactive in the code system but should still be included in the expansion.

3. For hosted content, the data-absent-reason extension with a value of unknown MAY be used to satisfy required cardinality constraints of the Shareable and Publishable value set profiles when an element is not present in the source of truth for the content.

4. ValueSet resources returned by the repository SHALL use the meta.profile element to indicate which profiles the ValueSet conforms to, Shareable, Publishable, Computable, or Expanded.

5. SHALL Represent expanded ValueSet information, as specified by the CRMIExpandedValueSet profile, which specifies the complete content of a value set using the `expansion` element, including inactive codes specified in the compose.

6. For published ValueSets, SHALL represent publishable ValueSet information, as specified by the CRMIPublishableValueSet profile.

7. SHALL support ValueSet read, by the server-defined id for the ValueSet

8. SHALL support ValueSet searches by:
   1. url: Returning all versions of the valueset matching that url
   2. version: Returning the valueset matching that version (can appear only in combination with a url search)
   3. identifier: Returning any valueset matching the identifier
   4. name: Returning any valueset matching the name, according to the string-matching semantics in FHIR
   5. title: Returning any valueset matching the title, according to the string-matching semantics in FHIR
   6. status: Returning valuesets that match the given status
   7. description: Returning any valueset matching the search description, according to string-matching semantics in FHIR
   8. code: Returning any valueset with the given code
   9. keyword: Returning any valueset that has a valueset-keyword extension matching the given keyword
9. SHOULD support ValueSet searches by:
   1. context: Returning all artifacts with a use context value matching the given context
   2. context-type: Returning all artifacts with a use context type matching the given context type
   3. context-type-quantity: Returning all artifacts with a use context quantity or range matching the given quantity
   4. context-type-value: Returning all artifacts with a given use context type and value
   5. codesystem: Returning any valueset that directly references the given codesystem url (optionally versioned)
   6. valueset: Returning any valueset that references or is referenced by the given valueset url (optionally versioned)
   7. library: Returning any valueset that is referenced by the given library url (optionally versioned)
   8. artifact: Returning any valueset that directly or indirectly references or is referenced by the given artifact url (optionally versioned)
   9. Servers SHOULD support the _text and _content search parameters (as described in the base specification
   10. expansion: MAY support the expansion parameter in combination with url or identifier (and optionally version), returning a ValueSet instance with the given expansion identifier.
10. SHALL Support ValueSet/$validate-code
    1. SHALL support the url parameter
    2. SHALL support the valueSetVersion parameter
    3. SHALL support the activeOnly parameter
    4. SHALL support the displayLanguage parameter
    5. SHALL support the code parameter
    6. SHALL support the system parameter
    7. SHALL support the systemVersion parameter
    8. SHALL support the coding parameter
    9. SHALL support the codeableConcept parameter
11. Support ValueSet/$expand
    1. SHALL support the url parameter
    2. SHALL support the valueSetVersion parameter
    3. SHALL support the activeOnly parameter
    4. SHALL support the displayLanguage parameter
    5. SHALL support the limitedExpansion parameter
    6. SHALL support the default-to-latest-version parameter
    7. SHALL support the system-version parameter
    8. SHALL support the check-system-version parameter
    9. SHALL support the force-system-version parameter
    10. SHALL support the canonicalVersion parameter (defined in the crmi-valueset-expand)
    11. SHALL support the checkCanonicalVersion (defined in the crmi-valueset-expand)
    12. SHALL support the forceCanonicalVersion (defined in the crmi-valueset-expand)
    13. SHOULD support includeDesignation parameter
    14. SHOULD support designation parameter
    15. SHOULD support paging parameters
    16. SHOULD support the `manifest` parameter (defined in the crmi-valueset-expand)
    17. MAY support the `expansion` parameter (defined in the crmi-valueset-expand)
    18. SHOULD support the `includeDraft` parameter (defined in the crmi-valueset-expand)

### Artifact Collections

1. SHALL Represent basic artifact collection information, as specified by the CRMIManifestLibrary profile, which includes identifier, title, type, date, useContext, effectivePeriod, and terminology references

2. For published artifact collections, SHALL represent publishable artifact collection information as specified by the CRMIPublishableLibrary profile.

3. SHALL support Library read, by the server-defined id for the library

4. SHALL support Library searches by:
   1. url: Returning all versions of the library matching that url
   2. version: Returning the library matching that version (can appear only in combination with a url search)
   3. identifier: Returning any library matching the identifier
   4. name: Returning any library matching the name, according to the string-matching semantics in FHIR
   5. title: Returning any library matching the title, according to the string-matching semantics in FHIR
   6. status: Returning libraries that match the given status
   7. description: Returning any libraries matching the search description, according to string-matching semantics in FHIR
   8. composed-of: Returning any library that includes the given measure canonical or quality program version manifest or release
   9. depends-on: Returning any library that references the given code system or value set canonical
   10. part-of: Returning any version manifest or release that is part of the given library
5. SHALL support specifying expansion rules for the following $expand parameters
   1. SHALL support the activeOnly parameter
   2. SHALL support the system-version parameter
   3. SHALL support the check-system-version parameter
   4. SHALL support the force-system-version parameter
   5. SHOULD support the `includeDraft` parameter (defined in the crmi-valueset-expand)
   6. SHOULD support other parameters
   7. MAY support the `expansion` parameter (defined in the crmi-valueset-expand)
6. Because this capability results in the potential for parameter values to be supplied in multiple places, the following rules apply:
   1. If a parameter is specified as part of the $expand operation directly, it takes precedence
   2. If a ValueSet dependency is specified as part of the version manifest (and no version for the value set is specified in the artifact reference), the version has the same meaning as the `valueSetVersion` parameter to the $expand
   3. If a CodeSystem dependency is specified as part of the version manifest (and no version for the code system is specified in the artifact reference), the version has the same meaning as the `system-version` parameter to the $expand
   4. Version information specified in the expansion parameters takes precedence over version information specified as part of the version manifest (i.e. as a relatedArtifact dependency in the artifact collection library)
7. SHALL support version manifest and release value set packaging: Library/$package operation
   1. SHALL support the url parameter
   2. SHALL support the version parameter
   3. SHOULD support the offset parameter
   4. SHOULD support the count parameter
   5. SHOULD support canonicalVersion parameter (overrides any canonical resource versions specified in the manifest)
   6. SHOULD support checkCanonicalVersion parameter (overrides any canonical resource versions specified in the manifest)
   7. SHOULD support forceCanonicalVersion parameter (overrides any canonical resource versions specified in the manifest)
   8. SHOULD support system-version parameter (overrides code system versions specified in the quality program release)
   9. SHOULD support check-system-version parameter (overrides code system versions specified in the quality program release)
   10. SHOULD support force-system-version parameter (overrides code system versions specified in the quality program release)
8. SHALL support operations to enable maintenance of release specifications for artifact collections using Library resources that conform to the CRMIManifestLibrary profile.
   1. SHALL support creating a Library in `draft` status (using POST)
   2. SHALL support updating a Library in `draft` status (using PUT)
   3. SHALL support updating the status of a Library in `draft` to `active` (using PUT)
   4. SHALL support updating the status of a Library in `active` status to `retired` (using PUT)
   5. SHALL reject attempts to update elements of a Library other than status if the Library is not in `draft` status
   6. SHALL reject attempts to create Libraries that have the same `url` and `version` as another library

### Server Operations

1. SHALL support the `metadata?mode=terminology`, returning a list of all supported code systems, whether they are explicitly made available as CodeSystem resources or not

2. To ensure performant operations with large code systems and value sets, a measure terminology service SHALL support batch operations for at least the following:
   1. CodeSystem read
   2. CodeSystem search
   3. CodeSystem/$validate-code
   4. ValueSet read
   5. ValueSet search
   6. ValueSet/$validate-code

3. Services MAY require authentication. If authentication is required, it SHALL be in the form of an authentication header (usually a bearer token) that the user can determine in advance and provide to their FHIR tooling in some configuration.

4. For all string search parameters, servers:
   1. SHALL support the `contains` and `exact` modifiers
   2. SHOULD support `text`
5. Servers SHALL support the expression of AND and OR search parameters for all search parameters, as defined in the composite search parameter topic

### Capability Statement

The above capabilities are formally captured in the following capability statement:

CRMIArtifactTerminologyService

### Examples

#### Expansion of a value set that contains “legacy codes”

This is the computable representation of an example Chronic Liver Disease value set. It contains two concepts that are active (as of the 2019-09 release of the US Edition of SNOMED-CT) and one concept that was last active in the 2015-03 release).

- ChronicLiverDiseaseLegacyExample

The `compose` element of this value set is:

    "compose": {
      "include": [
        {
          "system": "http://snomed.info/sct",
          "concept": [
            {
              "code": "1116000",
              "display": "Chronic aggressive type B viral hepatitis (disorder)"
            },
            {
              "code": "10295004",
              "display": "Chronic viral hepatitis (disorder)"
            }
          ]
        },
        {
          "system": "http://snomed.info/sct",
          "version": "http://snomed.info/sct/731000124108/version/20150301",
          "concept": [
            {
              "code": "111370006",
              "display": "Cirrhosis of liver not due to alcohol (disorder)"
            }
          ]
        }
      ]
    }

Note specifically the use of the `inactive` element to indicate that the value set definition contains inactive codes, and the use of separate `include` elements, one for the codes that do not specify a code system version, and one for the legacy code from version `http://snomed.info/sct/731000124108/version/20150301`.

##### Current expand

Given the following `$expand`:

    [base]/ValueSet/chronic-liver-disease-legacy-example/$expand

The expected result expansion is:

    "expansion": {
      "timestamp": "2021-02-05T08:57:00-06:00",
      "contains": [
        {
          "system": "http://snomed.info/sct",
          "code": "1116000",
          "display": "Chronic aggressive type B viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "code": "10295004",
          "display": "Chronic viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "inactive": true,
          "code": "111370006",
          "display": "Cirrhosis of liver not due to alcohol (disorder)"
        }
      ]
    }

Note the use of the `inactive` element to indicate the code `111370006` is inactive in the current version of SNOMED (i.e. the version of SNOMED that was active when this expansion was produced, and the use of the `timestamp` to ensure that date is known).

##### Current expand, activeOnly

Given the following `$expand`:

    [base]/ValueSet/chronic-liver-disease-legacy-example/$expand?activeOnly=true

The expected result expansion is:

    "expansion": {
      "timestamp": "2021-02-05T08:57:00-06:00",
      "parameter": [
        {
          "name": "activeOnly",
          "valueBoolean": true
        }
      ],
      "contains": [
        {
          "system": "http://snomed.info/sct",
          "code": "1116000",
          "display": "Chronic aggressive type B viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "code": "10295004",
          "display": "Chronic viral hepatitis (disorder)"
        }
      ]
    }

The result of the `activeOnly` parameter is to exclude the inactive code, even though it was explicitly included in the value set definition.

##### Version-specific expand

Given the following `$expand`:

    [base]/ValueSet/chronic-liver-disease-legacy-example/$expand?valueSetVersion=2020-05&system-version=http://snomed.info/sct|http://snomed.info/sct/731000124108/version/20150301

The expected result expansion is:

    "expansion": {
      "timestamp": "2021-02-05T08:57:00-06:00",
      "parameter": [
        {
          "name": "valueSetVersion",
          "valueString": "2020-05"
        },
        {
          "name": "system-version",
          "valueUri": "http://snomed.info/sct|http://snomed.info/sct/731000124108/version/20190901"
        }
      ],
      "contains": [
        {
          "system": "http://snomed.info/sct",
          "code": "1116000",
          "display": "Chronic aggressive type B viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "code": "10295004",
          "display": "Chronic viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "inactive": true,
          "code": "111370006",
          "display": "Cirrhosis of liver not due to alcohol (disorder)"
        }
      ]
    }

Note this expansion contains the same codes as the `current` example, but is explicitly bound to the 2019-09 version of the US Edition of the SNOMED code system (http://snomed.info/sct/731000124108/version/20190901).

#### Artifact Collections

From the perspective of artifact development, artifact collections are used to represent collections of artifacts in 2 different ways:

1. As an organizer for an overall collection that contains version manifests and releases over time.
2. As a collection definition that provides version bindings and expansion rules for the artifacts in the collection.

Note that as the artifacts in the collection are developed, different aspects of the definition will be specified at different points of the process. For example, the initial definition will typically include a set of artifacts, as well as an initial set of proposed code system versions to be used. This provides for stable expansion of value sets while the artifacts are being developed. As development progresses, more and more aspects of the collection definition are finalized, resulting in more versions being pinned down. To illustrate these usages, we provide three artifact collection examples, one to illustrate the overall definition of a collection, one to illustrate the selection of code systems at the beginning of a development cycle, and one to illustrate a final release of a collection definition with artifact versions, value set versions, and code system versions completely specified.

##### Collection Example

The following example illustrates an overall collection that contains multiple version manifests and releases over time:

- Manifest Library

Note that as an organizer, this library just contains the collection-level information.

##### Draft Collection Example

This example illustrates the use of a draft quality program description to specify the version of SNOMED to be used for valuesets used by artifacts in the quality program.

    "contained": [
      {
        "resourceType": "Parameters",
        "id": "exp-params",
        "parameter": [
          {
            "name" : "system-version",
            "valueUri" : "http://snomed.info/sct|http://snomed.info/sct/731000124108/version/20190901"
          },
          {
            "name": "activeOnly",
            "valueBoolean": true
          },
          {
            "name": "includeDraft",
            "valueBoolean": true
          }
        ]
      }
    ],
    "extension": [
      {
        "url": "http://hl7.org/fhir/uv/crmi/StructureDefinition/crmi-expansionParameters",
        "valueReference": {
          "reference": "#exp-params"
        }
      }
    ],

This example indicates that unless specified explicitly by artifacts in the collection, the 2019-09-01 version of SNOMED SHALL be used when expanding value sets that reference SNOMED.

Note that the version of SNOMED in use is still listed as a dependency in the artifact collection to support providing a complete listing of dependencies in the version manifest. When this is done, the version provided in the expansion parameters SHALL take precedence (though the version manifest SHOULD be consistent with the expansion parameters).

    "relatedArtifact": [
      {
        "type": "depends-on",
        "resource": "http://snomed.info/sct|http://snomed.info/sct/731000124108/version/20190901",
        "display": "SNOMED-CT US Edition, 2019-09-01"
      }
    ]

##### Release Artifact Collection

The following example illustrates a collection that is an active instance of an artifact collection release used to provide stable extensions for the released artifacts in the collection.

Specifically, the collection release uses the `expansion` parameter in the contained expansion parameters at the artifact collection level to indicate that all value sets used with artifacts in the program should expand using this expansion identifier:

    {
      "name": "expansion",
      "valueUri": "eCQM%20Update%202020-05-07"
    }

In addition, the collection release specifies versions of code systems, value sets, and artifacts included in the release:

    {
      "type": "depends-on",
      "resource": "http://snomed.info/sct|http://snomed.info/sct/731000124108/version/20190901",
      "display": "SNOMED-CT US Edition, 2019-09-01"
    },
    {
      "type": "depends-on",
      "resource": "http://hl7.org/fhir/uv/crmi/ValueSet/chronic-liver-disease-legacy-example|2020-05",
      "display": "Chronic Liver Disease, Legacy Example (2020-05)"
    },
    {
      "type": "composed-of",
      "resource": "http://hl7.org/fhir/uv/crmi/Measure/measure-exm124-FHIR|9.0.0",
      "display": "Cervical Cancer Screening"
    },
    {
      "type": "composed-of",
      "resource": "http://hl7.org/fhir/uv/crmi/Measure/measure-exm125-FHIR",
      "display": "Breast Cancer Screening"
    },
    {
      "type": "composed-of",
      "resource": "http://hl7.org/fhir/uv/crmi/Measure/measure-exm130-FHIR",
      "display": "Colorectal Cancer Screening"
    },
    {
      "type": "composed-of",
      "resource": "http://hl7.org/fhir/uv/crmi/Measure/measure-exm146-FHIR",
      "display": "Appropriate Testing for Children with Pharyngitis"
    }

##### Expansion with manifests and releases:

Given this use of an artifact collection, the manifest parameter can be used in the `$expand` operation to provide values for the relevant parameters:

    [base]/ValueSet/chronic-liver-disease-legacy-example/$expand?manifest=http://hl7.org/fhir/uv/crmi/Library/ecqm-update-2020

This is effectively an alternative mechanism for expressing the same value set and code system version specific expansion above, and results in the same expansion, with the additional `manifest` parameter:

    "expansion": {
      "timestamp": "2021-02-05T08:57:00-06:00",
      "parameter": [
        {
          "name": "valueSetVersion",
          "valueString": "2020-05"
        },
        {
          "name": "system-version",
          "valueUri": "http://snomed.info/sct|http://snomed.info/sct/731000124108/version/20190901"
        },
        {
          "name": "manifest",
          "valueUri": "http://hl7.org/fhir/uv/crmi/Library/ecqm-update-2020"
        }
      ],
      "contains": [
        {
          "system": "http://snomed.info/sct",
          "code": "1116000",
          "display": "Chronic aggressive type B viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "code": "10295004",
          "display": "Chronic viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "inactive": true,
          "code": "111370006",
          "display": "Cirrhosis of liver not due to alcohol (disorder)"
        }
      ]
    }

Similarly, when using a release for the manifest parameter:

    [base]/ValueSet/chronic-liver-disease-legacy-example/$expand?manifest=http://hl7.org/fhir/uv/crmi/Library/ecqm-update-2020-05-07

This is effectively the same as providing the `expansion` parameter to the value set expand, and results in the expansion with the specified expansion identifier:

    "expansion": {
      "identifier": "eCQM%20Update%202020-05-07",
      "timestamp": "2021-02-05T08:57:00-06:00",
      "parameter": [
        {
          "name": "valueSetVersion",
          "valueString": "2020-05"
        },
        {
          "name": "system-version",
          "valueUri": "http://snomed.info/sct|http://snomed.info/sct/731000124108/version/20190901"
        },
        {
          "name": "manifest",
          "valueUri": "http://hl7.org/fhir/uv/crmi/Library/ecqm-update-2020-05-07"
        }
      ],
      "contains": [
        {
          "system": "http://snomed.info/sct",
          "code": "1116000",
          "display": "Chronic aggressive type B viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "code": "10295004",
          "display": "Chronic viral hepatitis (disorder)"
        },
        {
          "system": "http://snomed.info/sct",
          "inactive": true,
          "code": "111370006",
          "display": "Cirrhosis of liver not due to alcohol (disorder)"
        }
      ]
    }

#### Value Set Searches

##### Expansion Search

In addition to the use of the `expansion` parameter of the `$expand` operation, terminology services SHOULD support searching for a particular ValueSet expansion using the `expansion` search parameter:

    [base]/ValueSet?url=http://hl7.org/fhir/uv/crmi/ValueSet/chronic-liver-disease-legacy-example&expansion=eCQM%20Update%202020-05-07

The result of this search is the same as requesting an `$expand` with the `expansion` parameter.

##### Summary Search

{}summary is a as either a SHOULD support search parameter. The {}summary{} search parameter would allow responding with partial-data sets of artifacts, which may be desirable to boost performance for certain actions.