StructureDefinition for code

{
  "resourceType" : "StructureDefinition",
  "id" : "code",
  "text" : {
    "status" : "generated",
    "div" : "<div xmlns=\"http://www.w3.org/1999/xhtml\">to do</div>"
  },
  "extension" : [{
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-standards-status",
    "valueCode" : "normative"
  },
  {
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-normative-version",
    "valueCode" : "4.0.0"
  },
  {
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-type-characteristics",
    "valueCode" : "can-bind"
  },
  {
    "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-type-characteristics",
    "valueCode" : "has-length"
  }],
  "url" : "http://hl7.org/fhir/StructureDefinition/code",
  "version" : "5.0.0-draft-final",
  "name" : "code",
  "status" : "active",
  "experimental" : false,
  "date" : "2023-03-01T23:03:57+11:00",
  "publisher" : "HL7 FHIR Standard",
  "contact" : [{
    "telecom" : [{
      "system" : "url",
      "value" : "http://hl7.org/fhir"
    }]
  }],
  "description" : "code type: A string which has at least one character and no leading or trailing whitespace and where there is no whitespace other than single spaces in the contents",
  "jurisdiction" : [{
    "coding" : [{
      "system" : "http://unstats.un.org/unsd/methods/m49/m49.htm",
      "code" : "001",
      "display" : "World"
    }]
  }],
  "fhirVersion" : "5.0.0-draft-final",
  "kind" : "primitive-type",
  "abstract" : false,
  "type" : "code",
  "baseDefinition" : "http://hl7.org/fhir/StructureDefinition/string",
  "derivation" : "specialization",
  "snapshot" : {
    "element" : [{
      "id" : "code",
      "path" : "code",
      "short" : "Primitive Type code",
      "definition" : "A string which has at least one character and no leading or trailing whitespace and where there is no whitespace other than single spaces in the contents",
      "min" : 0,
      "max" : "*",
      "base" : {
        "path" : "code",
        "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"
      }],
      "isModifier" : false,
      "isSummary" : false
    },
    {
      "id" : "code.id",
      "path" : "code.id",
      "representation" : ["xmlAttr"],
      "short" : "xml:id (or equivalent in JSON)",
      "definition" : "unique id for the element within a resource (for internal references)",
      "min" : 0,
      "max" : "1",
      "base" : {
        "path" : "Element.id",
        "min" : 0,
        "max" : "1"
      },
      "type" : [{
        "extension" : [{
          "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type",
          "valueUrl" : "string"
        }],
        "code" : "http://hl7.org/fhirpath/System.String"
      }],
      "isModifier" : false,
      "isSummary" : false
    },
    {
      "id" : "code.extension",
      "path" : "code.extension",
      "short" : "Additional content defined by implementations",
      "definition" : "May be used to represent additional information that is not part of the basic definition of the resource. To make the use of extensions safe and managable, there is a strict set of governance applied to the definition and use of extensions. Though any implementer can define an extension, there is a set of requirements that SHALL be met as part of the definition of the extension.",
      "comment" : "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.",
      "alias" : ["extensions",
      "user content"],
      "min" : 0,
      "max" : "*",
      "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" : "code.value",
      "path" : "code.value",
      "representation" : ["xmlAttr"],
      "short" : "Primitive value for code",
      "definition" : "Primitive value for code",
      "min" : 0,
      "max" : "1",
      "base" : {
        "path" : "string.value",
        "min" : 0,
        "max" : "1"
      },
      "type" : [{
        "extension" : [{
          "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type",
          "valueUrl" : "code"
        },
        {
          "url" : "http://hl7.org/fhir/StructureDefinition/regex",
          "valueString" : "[^\\s]+( [^\\s]+)*"
        }],
        "code" : "http://hl7.org/fhirpath/System.String"
      }],
      "isModifier" : false,
      "isSummary" : false
    }]
  },
  "differential" : {
    "element" : [{
      "id" : "code",
      "path" : "code",
      "short" : "Primitive Type code",
      "definition" : "A string which has at least one character and no leading or trailing whitespace and where there is no whitespace other than single spaces in the contents",
      "min" : 0,
      "max" : "*"
    },
    {
      "id" : "code.value",
      "path" : "code.value",
      "representation" : ["xmlAttr"],
      "short" : "Primitive value for code",
      "definition" : "Primitive value for code",
      "min" : 0,
      "max" : "1",
      "type" : [{
        "extension" : [{
          "url" : "http://hl7.org/fhir/StructureDefinition/structuredefinition-fhir-type",
          "valueUrl" : "code"
        },
        {
          "url" : "http://hl7.org/fhir/StructureDefinition/regex",
          "valueString" : "[^\\s]+( [^\\s]+)*"
        }],
        "code" : "http://hl7.org/fhirpath/System.String"
      }]
    }]
  }
}