FHIR Extensions Pack
5.2.0-ballot - 5.2.0 Ballot - September 2024) International flag

FHIR Extensions Pack, published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 5.2.0-ballot built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/fhir-extensions/ and changes regularly. See the Directory of published versions

Extension: PreferredTerminologyServer - JSON Profile

Page standards status: Trial-use Maturity Level: 4

JSON representation of the sdc-questionnaire-preferredTerminologyServer extension.

Raw json | Download

{
  "resourceType" : "StructureDefinition",
  "id" : "sdc-questionnaire-preferredTerminologyServer",
  "text" : {
    "status" : "extensions",
    "div" : "<div xmlns=\"http://www.w3.org/1999/xhtml\"><p class=\"res-header-id\"><b>Generated Narrative: StructureDefinition sdc-questionnaire-preferredTerminologyServer</b></p><a name=\"sdc-questionnaire-preferredTerminologyServer\"> </a><a name=\"hcsdc-questionnaire-preferredTerminologyServer\"> </a><a name=\"sdc-questionnaire-preferredTerminologyServer-en-US\"> </a><table border=\"0\" cellpadding=\"0\" cellspacing=\"0\" style=\"border: 0px #F0F0F0 solid; font-size: 11px; font-family: verdana; vertical-align: top;\"><tr style=\"border: 1px #F0F0F0 solid; font-size: 11px; font-family: verdana; vertical-align: top\"><th style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><a href=\"https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views\" title=\"The logical name of the element\">Name</a></th><th style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><a href=\"https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views\" title=\"Information about the use of the element\">Flags</a></th><th style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><a href=\"https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views\" title=\"Minimum and Maximum # of times the element can appear in the instance\">Card.</a></th><th style=\"width: 100px\" class=\"hierarchy\"><a href=\"https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views\" title=\"Reference to the type of the element\">Type</a></th><th style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><a href=\"https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views\" title=\"Additional information about the element\">Description &amp; Constraints</a><span style=\"float: right\"><a href=\"https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views\" title=\"Legend for this format\"><img src=\"data:image/png;base64,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\" alt=\"doco\" style=\"background-color: inherit\"/></a></span></th></tr><tr style=\"border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white\"><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck1.png)\" class=\"hierarchy\"><img src=\"tbl_spacer.png\" alt=\".\" style=\"background-color: inherit\" class=\"hierarchy\"/><img src=\"icon_element.gif\" alt=\".\" style=\"background-color: white; background-color: inherit\" title=\"Element\" class=\"hierarchy\"/> <a href=\"StructureDefinition-sdc-questionnaire-preferredTerminologyServer-definitions.html#Extension\" title=\"Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers.\">Extension</a><a name=\"Extension\"> </a></td><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"/><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><span style=\"opacity: 0.5\">0</span><span style=\"opacity: 0.5\">..</span><span style=\"opacity: 0.5\">*</span></td><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><a href=\"http://hl7.org/fhir/R5/extensibility.html#Extension\">Extension</a></td><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\">Preferred terminology server</td></tr>\r\n<tr style=\"border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: #F7F7F7\"><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck10.png)\" class=\"hierarchy\"><img src=\"tbl_spacer.png\" alt=\".\" style=\"background-color: inherit\" class=\"hierarchy\"/><img src=\"tbl_vjoin.png\" alt=\".\" style=\"background-color: inherit\" class=\"hierarchy\"/><img src=\"icon_extension_simple.png\" alt=\".\" style=\"background-color: #F7F7F7; background-color: inherit\" title=\"Simple Extension\" class=\"hierarchy\"/> <span style=\"text-decoration:line-through\">extension</span><a name=\"Extension.extension\"> </a></td><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"/><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><span style=\"text-decoration:line-through\"/><span style=\"text-decoration:line-through\">0</span><span style=\"text-decoration:line-through\">..</span><span style=\"text-decoration:line-through\">0</span></td><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"/><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"/></tr>\r\n<tr style=\"border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: white\"><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck10.png)\" class=\"hierarchy\"><img src=\"tbl_spacer.png\" alt=\".\" style=\"background-color: inherit\" class=\"hierarchy\"/><img src=\"tbl_vjoin.png\" alt=\".\" style=\"background-color: inherit\" class=\"hierarchy\"/><img src=\"icon_element.gif\" alt=\".\" style=\"background-color: white; background-color: inherit\" title=\"Element\" class=\"hierarchy\"/> <a href=\"StructureDefinition-sdc-questionnaire-preferredTerminologyServer-definitions.html#Extension.url\">url</a><a name=\"Extension.url\"> </a></td><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"/><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><span style=\"opacity: 0.5\">1</span><span style=\"opacity: 0.5\">..</span><span style=\"opacity: 0.5\">1</span></td><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><a style=\"opacity: 0.5\" href=\"http://hl7.org/fhir/R5/datatypes.html#uri\">uri</a></td><td style=\"vertical-align: top; text-align : left; background-color: white; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><span style=\"color: darkgreen\">&quot;http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer&quot;</span></td></tr>\r\n<tr style=\"border: 0px #F0F0F0 solid; padding:0px; vertical-align: top; background-color: #F7F7F7\"><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px; white-space: nowrap; background-image: url(tbl_bck00.png)\" class=\"hierarchy\"><img src=\"tbl_spacer.png\" alt=\".\" style=\"background-color: inherit\" class=\"hierarchy\"/><img src=\"tbl_vjoin_end.png\" alt=\".\" style=\"background-color: inherit\" class=\"hierarchy\"/><img src=\"icon_primitive.png\" alt=\".\" style=\"background-color: #F7F7F7; background-color: inherit\" title=\"Primitive Data Type\" class=\"hierarchy\"/> <a href=\"StructureDefinition-sdc-questionnaire-preferredTerminologyServer-definitions.html#Extension.value[x]\">value[x]</a><a name=\"Extension.value_x_\"> </a></td><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"/><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><span style=\"opacity: 0.5\">0</span><span style=\"opacity: 0.5\">..</span><span style=\"opacity: 0.5\">1</span></td><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><a href=\"http://hl7.org/fhir/R5/datatypes.html#url\">url</a></td><td style=\"vertical-align: top; text-align : left; background-color: #F7F7F7; border: 0px #F0F0F0 solid; padding:0px 4px 0px 4px\" class=\"hierarchy\"><span style=\"opacity: 0.5\">Value of extension</span></td></tr>\r\n<tr><td colspan=\"5\" class=\"hierarchy\"><br/><a href=\"https://build.fhir.org/ig/FHIR/ig-guidance/readingIgs.html#table-views\" title=\"Legend for this format\"><img src=\"data:image/png;base64,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\" alt=\"doco\" style=\"background-color: inherit\"/> Documentation for this format</a></td></tr></table></div>"
  },
  "extension" : [
    {
      "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-wg",
      "valueCode" : "fhir"
    },
    {
      "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fmm",
      "valueInteger" : 4,
      "_valueInteger" : {
        "extension" : [
          {
            "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-conformance-derivedFrom",
            "valueCanonical" : "http://hl7.org/fhir/uv/sdc/ImplementationGuide/hl7.fhir.uv.sdc"
          }
        ]
      }
    },
    {
      "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
      "valueCode" : "trial-use"
    },
    {
      "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-type-characteristics",
      "valueCode" : "can-bind"
    }
  ],
  "url" : "http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer",
  "version" : "5.2.0-ballot",
  "name" : "PreferredTerminologyServer",
  "title" : "Preferred Terminology Server",
  "status" : "active",
  "date" : "2024-12-16T04:47:21+00:00",
  "publisher" : "HL7 International / FHIR Infrastructure",
  "contact" : [
    {
      "name" : "HL7 International / FHIR Infrastructure",
      "telecom" : [
        {
          "system" : "url",
          "value" : "http://www.hl7.org/Special/committees/fiwg"
        }
      ]
    }
  ],
  "description" : "Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers.",
  "jurisdiction" : [
    {
      "coding" : [
        {
          "system" : "http://unstats.un.org/unsd/methods/m49/m49.htm",
          "code" : "001"
        }
      ]
    }
  ],
  "purpose" : "Not all terminology servers will necessarily have access to the codes.  If a questionnaire points to value sets, the rendering engine needs to know where to get a current expansion.",
  "fhirVersion" : "5.0.0",
  "mapping" : [
    {
      "identity" : "rim",
      "uri" : "http://hl7.org/v3",
      "name" : "RIM Mapping"
    }
  ],
  "kind" : "complex-type",
  "abstract" : false,
  "context" : [
    {
      "type" : "element",
      "expression" : "Questionnaire"
    },
    {
      "type" : "element",
      "expression" : "Questionnaire.item"
    },
    {
      "type" : "element",
      "expression" : "ElementDefinition"
    }
  ],
  "type" : "Extension",
  "baseDefinition" : "http://hl7.org/fhir/StructureDefinition/Extension",
  "derivation" : "constraint",
  "snapshot" : {
    "element" : [
      {
        "id" : "Extension",
        "path" : "Extension",
        "short" : "Preferred terminology server",
        "definition" : "Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers.",
        "min" : 0,
        "max" : "*",
        "base" : {
          "path" : "Extension",
          "min" : 0,
          "max" : "*"
        },
        "constraint" : [
          {
            "key" : "ele-1",
            "severity" : "error",
            "human" : "All FHIR elements must have a @value or children",
            "expression" : "hasValue() or (children().count() > id.count())",
            "source" : "http://hl7.org/fhir/StructureDefinition/Element"
          },
          {
            "key" : "ext-1",
            "severity" : "error",
            "human" : "Must have either extensions or value[x], not both",
            "expression" : "extension.exists() != value.exists()",
            "source" : "http://hl7.org/fhir/StructureDefinition/Extension"
          }
        ],
        "isModifier" : false
      },
      {
        "id" : "Extension.id",
        "path" : "Extension.id",
        "representation" : [
          "xmlAttr"
        ],
        "short" : "Unique id for inter-element referencing",
        "definition" : "Unique id for the element within a resource (for internal references). This may be any string value that does not contain spaces.",
        "min" : 0,
        "max" : "1",
        "base" : {
          "path" : "Element.id",
          "min" : 0,
          "max" : "1"
        },
        "type" : [
          {
            "extension" : [
              {
                "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type",
                "valueUrl" : "id"
              }
            ],
            "code" : "http://hl7.org/fhirpath/System.String"
          }
        ],
        "condition" : [
          "ele-1"
        ],
        "isModifier" : false,
        "isSummary" : false,
        "mapping" : [
          {
            "identity" : "rim",
            "map" : "n/a"
          }
        ]
      },
      {
        "id" : "Extension.extension",
        "path" : "Extension.extension",
        "slicing" : {
          "discriminator" : [
            {
              "type" : "value",
              "path" : "url"
            }
          ],
          "description" : "Extensions are always sliced by (at least) url",
          "rules" : "open"
        },
        "short" : "Extension",
        "definition" : "An Extension",
        "min" : 0,
        "max" : "0",
        "base" : {
          "path" : "Element.extension",
          "min" : 0,
          "max" : "*"
        },
        "type" : [
          {
            "code" : "Extension"
          }
        ],
        "constraint" : [
          {
            "key" : "ele-1",
            "severity" : "error",
            "human" : "All FHIR elements must have a @value or children",
            "expression" : "hasValue() or (children().count() > id.count())",
            "source" : "http://hl7.org/fhir/StructureDefinition/Element"
          },
          {
            "key" : "ext-1",
            "severity" : "error",
            "human" : "Must have either extensions or value[x], not both",
            "expression" : "extension.exists() != value.exists()",
            "source" : "http://hl7.org/fhir/StructureDefinition/Extension"
          }
        ],
        "isModifier" : false,
        "isSummary" : false
      },
      {
        "id" : "Extension.url",
        "path" : "Extension.url",
        "representation" : [
          "xmlAttr"
        ],
        "short" : "identifies the meaning of the extension",
        "definition" : "Source of the definition for the extension code - a logical name or a URL.",
        "comment" : "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.",
        "min" : 1,
        "max" : "1",
        "base" : {
          "path" : "Extension.url",
          "min" : 1,
          "max" : "1"
        },
        "type" : [
          {
            "extension" : [
              {
                "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type",
                "valueUrl" : "uri"
              }
            ],
            "code" : "http://hl7.org/fhirpath/System.String"
          }
        ],
        "fixedUri" : "http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer",
        "isModifier" : false,
        "isSummary" : false,
        "mapping" : [
          {
            "identity" : "rim",
            "map" : "N/A"
          }
        ]
      },
      {
        "id" : "Extension.value[x]",
        "path" : "Extension.value[x]",
        "short" : "Value of extension",
        "definition" : "Value of extension - must be one of a constrained set of the data types (see [Extensibility](http://hl7.org/fhir/R5/extensibility.html) for a list).",
        "min" : 0,
        "max" : "1",
        "base" : {
          "path" : "Extension.value[x]",
          "min" : 0,
          "max" : "1"
        },
        "type" : [
          {
            "code" : "url"
          }
        ],
        "condition" : [
          "ext-1"
        ],
        "constraint" : [
          {
            "key" : "ele-1",
            "severity" : "error",
            "human" : "All FHIR elements must have a @value or children",
            "expression" : "hasValue() or (children().count() > id.count())",
            "source" : "http://hl7.org/fhir/StructureDefinition/Element"
          }
        ],
        "isModifier" : false,
        "isSummary" : false,
        "mapping" : [
          {
            "identity" : "rim",
            "map" : "N/A"
          }
        ]
      }
    ]
  },
  "differential" : {
    "element" : [
      {
        "id" : "Extension",
        "path" : "Extension",
        "short" : "Preferred terminology server",
        "definition" : "Indicates the terminology server(s) that are known to be capable of returning and potentially expanding the value set(s) associated with the resource or a particular portion of the resource (depending on where the extension appears).  If a full URL is not provided AND the requested query is a terminology operation (e.g. $lookup or $expand) the client SHOULD execute the operation against (one of) the preferredTerminologyServer(s) rather than the local repository. Systems SHOULD evaluate value sets using terminology servers as follows:  First, try any terminology servers declared on the element in question.  If there are more then one, try them in the order they appear.  Then try any servers that appear on ancestor elements in order of closest ancestor up to any on the resource root  If there are no declared servers or none of the ones listed provide a useful response, the form filler may then try any of the typical servers it would normally use.  A 'useful response' means a response that provides a valid (though potentially empty) expansion.  Clients MAY wish to log/report errors returned by terminology servers."
      },
      {
        "id" : "Extension.extension",
        "path" : "Extension.extension",
        "max" : "0"
      },
      {
        "id" : "Extension.url",
        "path" : "Extension.url",
        "fixedUri" : "http://hl7.org/fhir/StructureDefinition/preferredTerminologyServer"
      },
      {
        "id" : "Extension.value[x]",
        "path" : "Extension.value[x]",
        "type" : [
          {
            "code" : "url"
          }
        ]
      }
    ]
  }
}