openapi: 3.0.0

info:
  title: SEALDD Server Data Transmission Service
  version: 1.1.1
  description: |
    SEALDD Server Data Transmission Service.  
    © 2026, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC).  
    All rights reserved.

externalDocs:
  description: >
    3GPP TS 29.548 V19.6.0; Service Enabler Architecture Layer for Verticals (SEAL);
    SEAL Data Delivery (SEALDD) Server Services; Stage 3.
  url: https://www.3gpp.org/ftp/Specs/archive/29_series/29.548/

servers:
  - url: '{apiRoot}/sdd-trans/v1'
    variables:
      apiRoot:
        default: https://example.com
        description: apiRoot as defined in clause 6.5 of 3GPP TS 29.549

security:
  - {}
  - oAuth2ClientCredentials: []

paths:
  /{transType}/request-trans:
    parameters:
      - name: transType
        in: path
        description: >
          Represents the requested transmission type.
        required: true
        schema:
          $ref: '#/components/schemas/TransType'

    post:
      summary: Request SEALDD enabled Data Transmission.
      operationId: RequestTrans
      tags:
        - Request SEALDD Data Transmission
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransReq'
      responses:
        '200':
          description: >
            OK. The SEALDD enabled application data transmission service request
            was successfully received and processed.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TransResp'
        '307':
          $ref: 'TS29122_CommonData.yaml#/components/responses/307'
        '308':
          $ref: 'TS29122_CommonData.yaml#/components/responses/308'
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '411':
          $ref: 'TS29122_CommonData.yaml#/components/responses/411'
        '413':
          $ref: 'TS29122_CommonData.yaml#/components/responses/413'
        '415':
          $ref: 'TS29122_CommonData.yaml#/components/responses/415'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

  /subscriptions:
    post:
      summary: Request the Creation of a new Connection Status Subscription.
      operationId: CreateConnStatusSubsc
      tags:
        - Connection Status Subscriptions (Collection)
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ConnStatusSubsc'
      responses:
        '201':
          description: >
            Successful case. The requested Connection Status Subscription resource is successfully
            created and a representation of the created "Individual Connection Status Subscription"
            resource is returned in the response body.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ConnStatusSubsc'
          headers:
            Location:
              description: >
                Contains the URI of the newly created Individual Connection Status Subscription
                resource.
              required: true
              schema:
                type: string
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '411':
          $ref: 'TS29122_CommonData.yaml#/components/responses/411'
        '413':
          $ref: 'TS29122_CommonData.yaml#/components/responses/413'
        '415':
          $ref: 'TS29122_CommonData.yaml#/components/responses/415'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'
      callbacks:
        ConnStatusNotif:
          '{$request.body#/notifUri}': 
            post:
              summary: Notify a previously subscribed service consumer on SEALDD connection status event(s).
              requestBody:
                required: true
                content:
                  application/json:
                    schema:
                      $ref: '#/components/schemas/ConnStatusNotif'
              responses:
                '204':
                  description: >
                    Successful case. The Connection Status Notification is successfully received.
                '307':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/307'
                '308':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/308'
                '400':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/400'
                '401':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/401'
                '403':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/403'
                '404':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/404'
                '411':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/411'
                '413':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/413'
                '415':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/415'
                '429':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/429'
                '500':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/500'
                '503':
                  $ref: 'TS29122_CommonData.yaml#/components/responses/503'
                default:
                  $ref: 'TS29122_CommonData.yaml#/components/responses/default'

  /subscriptions/{subscriptionId}:
    parameters:
      - name: subscriptionId
        in: path
        description: >
          Represents the identifier of the Individual Connection Status Subscription resource.
        required: true
        schema:
          type: string

    get:
      summary: Retrieve an existing Individual Connection Status Subscription resource.
      operationId: GetIndConnStatusSubsc
      tags:
        - Individual Connection Status Subscription (Document)
      responses:
        '200':
          description: >
            OK. The requested Individual Connection Status Subscription resource shall be returned.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ConnStatusSubsc'
        '307':
          $ref: 'TS29122_CommonData.yaml#/components/responses/307'
        '308':
          $ref: 'TS29122_CommonData.yaml#/components/responses/308'
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '406':
          $ref: 'TS29122_CommonData.yaml#/components/responses/406'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

    put:
      summary: Request the update of an existing Individual Connection Status Subscription resource.
      operationId: UpdateIndConnStatusSubsc
      tags:
        - Individual Connection Status Subscription (Document)
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ConnStatusSubsc'
      responses:
        '200':
          description: >
            OK. The Individual Connection Status Subscription resource is successfully updated and
            a representation of the updated resource shall be returned in the response body.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ConnStatusSubsc'
        '204':
          description: >
            No Content. The Individual Connection Status Subscription resource is successfully
            updated and no content is returned in the response body.
        '307':
          $ref: 'TS29122_CommonData.yaml#/components/responses/307'
        '308':
          $ref: 'TS29122_CommonData.yaml#/components/responses/308'
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '411':
          $ref: 'TS29122_CommonData.yaml#/components/responses/411'
        '413':
          $ref: 'TS29122_CommonData.yaml#/components/responses/413'
        '415':
          $ref: 'TS29122_CommonData.yaml#/components/responses/415'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

    patch:
      summary: Request the modification of an existing Individual Connection Status Subscription resource.
      operationId: ModifyIndConnStatusSubsc
      tags:
        - Individual Connection Status Subscription (Document)
      requestBody:
        required: true
        content:
          application/merge-patch+json:
            schema:
              $ref: '#/components/schemas/ConnStatusSubscPatch'
      responses:
        '200':
          description: >
            OK. The Individual Connection Status Subscription resource is successfully modified
            and a representation of the updated resource shall be returned in the response body.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ConnStatusSubsc'
        '204':
          description: >
            No Content. The Individual Connection Status Subscription resource is successfully
            modified and no content is returned in the response body.
        '307':
          $ref: 'TS29122_CommonData.yaml#/components/responses/307'
        '308':
          $ref: 'TS29122_CommonData.yaml#/components/responses/308'
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '411':
          $ref: 'TS29122_CommonData.yaml#/components/responses/411'
        '413':
          $ref: 'TS29122_CommonData.yaml#/components/responses/413'
        '415':
          $ref: 'TS29122_CommonData.yaml#/components/responses/415'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'

    delete:
      summary: Request the deletion of an existing Individual Connection Status Subscription resource.
      operationId: DeleteIndConnStatusSubsc
      tags:
        - Individual Connection Status Subscription (Document)
      responses:
        '204':
          description: >
            No Content. The Individual Connection Status Subscription resource is successfully
            deleted.
        '307':
          $ref: 'TS29122_CommonData.yaml#/components/responses/307'
        '308':
          $ref: 'TS29122_CommonData.yaml#/components/responses/308'
        '400':
          $ref: 'TS29122_CommonData.yaml#/components/responses/400'
        '401':
          $ref: 'TS29122_CommonData.yaml#/components/responses/401'
        '403':
          $ref: 'TS29122_CommonData.yaml#/components/responses/403'
        '404':
          $ref: 'TS29122_CommonData.yaml#/components/responses/404'
        '429':
          $ref: 'TS29122_CommonData.yaml#/components/responses/429'
        '500':
          $ref: 'TS29122_CommonData.yaml#/components/responses/500'
        '503':
          $ref: 'TS29122_CommonData.yaml#/components/responses/503'
        default:
          $ref: 'TS29122_CommonData.yaml#/components/responses/default'


components:
  securitySchemes:
    oAuth2ClientCredentials:
      type: oauth2
      flows:
        clientCredentials:
          tokenUrl: '{tokenUrl}'
          scopes: {}

  schemas:

#
# STRUCTURED DATA TYPES
#

    TransReq:
      description: >
        Represents the parameters to request the SEALDD enabled application data
        transmission service.
      type: object
      properties:
        valServiceId:
          type: string
        valTargetId:
          $ref: 'TS29549_SS_UserProfileRetrieval.yaml#/components/schemas/ValTargetUe'
        valServerConnInfo:
          $ref: '#/components/schemas/ConnInfo'
        multiModalId:
          $ref: 'TS29514_Npcf_PolicyAuthorization.yaml#/components/schemas/MultiModalId'
        multiModalFlows:
          type: array
          items:
            $ref: '#/components/schemas/MultiModalFlowInfo'
          minItems: 1
        qosInfo:
          $ref: '#/components/schemas/QosInfo'
        valServerBdw:
          $ref: '#/components/schemas/ValServBdw'
        valUsersBdw:
          $ref: '#/components/schemas/ValUsersBdw'
        connStatusSubsc:
          $ref: '#/components/schemas/SatConnStatusSubsc'
        suppFeat:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/SupportedFeatures'
      allOf:
        - oneOf:
          - required: [valServerConnInfo]
          - required: [multiModalFlows]
        - not:
            required: [multiModalFlows, qosInfo]

    TransResp:
      description: >
        Represents a SEALDD enabled application data transmission service response.
      type: object
      properties:
        ddServerConnInfo:
          $ref: '#/components/schemas/ConnInfo'
        connStatusSubsc:
          $ref: '#/components/schemas/SatConnStatusSubsc'
        suppFeat:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/SupportedFeatures'

    ConnInfo:
      description: >
        Represents SEALDD connection information.
      type: object
      properties:
        ipv4Addr:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/Ipv4Addr'
        ipv6Addr:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/Ipv6Addr'
        port:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Port'
        uri:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Uri'
      oneOf:
        - required: [ipv4Addr]
        - required: [ipv6Addr]
        - required: [uri]

    QosInfo:
      description: >
        Represents SEALDD related QoS requirements.
      type: object
      properties:
        qosReference:
          type: string
        altQoSReferences:
          type: array
          items:
            type: string
          minItems: 1
        altQosReqs:
          type: array
          items:
            $ref: 'TS29514_Npcf_PolicyAuthorization.yaml#/components/schemas/AlternativeServiceRequirementsData'
          minItems: 1
      anyOf:
        - required: [qosReference]
        - required: [altQoSReferences]
        - required: [altQosReqs]
        - not:
            required: [altQoSReferences, altQosReqs]
        - not:
            required: [qosReference, altQosReqs]

    ValServBdw:
      description: >
        Represents VAL Server related bandwidth information.
      type: object
      properties:
        totalUlBdw:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Bandwidth'
        totalDlBdw:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Bandwidth'
      required:
        - totalUlBdw
        - totalDlBdw

    ValUsersBdw:
      description: >
        Represents VAL users related bandwidth information.
      type: object
      properties:
        minUlBdw:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Bandwidth'
        minDlBdw:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Bandwidth'
        maxUlBdw:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Bandwidth'
        maxDlBdw:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Bandwidth'
      required:
        - minUlBdw
        - minDlBdw
        - maxUlBdw
        - maxDlBdw

    ConnStatusSubsc:
      description: >
        Represents a Connection Status Subscription.
      type: object
      properties:
        events:
          type: array
          items:
            $ref: '#/components/schemas/ConnStatusEvent'
          minItems: 1
          description: >
            Represents the subscribed event(s).
        valServiceId:
          type: string
        valTgtUe:
          $ref: 'TS29549_SS_UserProfileRetrieval.yaml#/components/schemas/ValTargetUe'
        valServerConnInfo:
          $ref: '#/components/schemas/ConnInfo'
        immRep:
          type: boolean
          description: >
            Represents a Connection Status Subscription.
            true indicates that immediate reporting is requested.
            false indicates that immediate reporting is not requested.
            The default value is false when this attribute is omitted.
        reports:
          type: array
          items:
            $ref: '#/components/schemas/ConnStatusReport'
          minItems: 1
        connStatusPer:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        notifUri:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Uri'
        expTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DateTimeRo'
        non3gppMeasInfo:
          $ref: 'TS29548_SDD_PolicyConfiguration.yaml#/components/schemas/Non3gppAccessMeasPol'
        suppFeat:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/SupportedFeatures'
      required:
        - events
        - valServerConnInfo
        - notifUri

    ConnStatusSubscPatch:
      description: >
        Represents the requested modifications to a Connection Status Subscription.
      type: object
      properties:
        events:
          type: array
          items:
            $ref: '#/components/schemas/ConnStatusEvent'
          minItems: 1
        valServiceId:
          type: string
        valTgtUe:
          $ref: 'TS29549_SS_UserProfileRetrieval.yaml#/components/schemas/ValTargetUe'
        valServerConnInfo:
          $ref: '#/components/schemas/ConnInfo'
        connStatusPer:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        notifUri:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Uri'

    ConnStatusNotif:
      description: >
        Represents a Connection Status Notification.
      type: object
      properties:
        subscriptionId:
          type: string
        reports:
          type: array
          items:
            $ref: '#/components/schemas/ConnStatusReport'
          minItems: 1
      required:
        - subscriptionId
        - reports

    ConnStatusReport:
      description: >
        Represents a Connection Status Event report.
      type: object
      properties:
        event:
          $ref: '#/components/schemas/ConnStatusEvent'
        valTgtUe:
          $ref: 'TS29549_SS_UserProfileRetrieval.yaml#/components/schemas/ValTargetUe'
        valServiceId:
          type: string
        connEstData:
          $ref: '#/components/schemas/ConnEstabData'
        clientConnStat:
          $ref: '#/components/schemas/ClientConnStatus'
        congestLevel:
          type: integer
          minimum: 0
          maximum: 100
        dlDelInstrucs:
          $ref: '#/components/schemas/DLDelInstructions'
        timestamp:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DateTime'
      required:
        - event
        - valTgtUe
        - valServiceId

    ConnEstabData:
      description: >
        Represents SEALDD connection status establishment data.
      type: object
      properties:
        ddServerConnInfo:
          $ref: '#/components/schemas/ConnInfo'
        comLifetime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
      required:
        - ddServerConnInfo

    ProtocolDesc:
      description: >
        Represents the protocol description information for Multi-modal application data
        transmission.
      type: object
      properties:
        dlDescInfo:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/ProtocolDescription'
        ulDescInfo:
          $ref: 'TS29571_CommonData.yaml#/components/schemas/ProtocolDescription'
        packetizationInd:
          type: boolean
          default: false
          description: >
            Contains the packetization indication.
            true indicates that packetization is requested.
            false indicates that packetization is not requested.
            The default value is false when this attribute is omitted.
      anyOf:
        - required: [dlDescInfo]
        - required: [ulDescInfo]

    SatConnStatusSubsc:
      description: >
        Represents a Connection Status Subscription relative to the S&F Satellite application data
        transmission.
      type: object
      properties:
        events:
          type: array
          items:
            $ref: '#/components/schemas/ConnStatusEvent'
          minItems: 1
          description: >
            Represents the subscribed event(s).
        valServiceId:
          type: string
        valTgtUe:
          $ref: 'TS29549_SS_UserProfileRetrieval.yaml#/components/schemas/ValTargetUe'
        valServerConnInfo:
          $ref: '#/components/schemas/ConnInfo'
        immRep:
          type: boolean
        reports:
          type: array
          items:
            $ref: '#/components/schemas/ConnStatusReport'
          minItems: 1
        connStatusPer:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DurationSec'
        notifUri:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/Uri'
        expTime:
          $ref: 'TS29122_CommonData.yaml#/components/schemas/DateTimeRo'
      required:
        - events
        - valServerConnInfo
        - notifUri

    MultiModalFlowInfo:
      description: >
        Represents the multi-modal flow related application data transmission information.
      type: object
      properties:
        valServerConnInfo:
          $ref: '#/components/schemas/ConnInfo'
        qosInfo:
          $ref: '#/components/schemas/QosInfo'
        protocolDesc:
          $ref: '#/components/schemas/ProtocolDesc'
      required:
        - valServerConnInfo


# SIMPLE DATA TYPES
#

#
# ENUMERATIONS
#

    ConnStatusEvent:
      anyOf:
      - type: string
        enum:
           - ESTABLISHED
           - RELEASED
           - CLIENT_CONN_STATUS
           - CONGESTION
           - DL_DEL_INSTRUCTIONS
      - type: string
        description: >
          This string provides forward-compatibility with future extensions to the enumeration
          and is not used to encode content defined in the present version of this API.
      description: |
        Represents Connection Status Events.  
        Possible values are:
        - ESTABLISHED: Indicates that the SEALDD connection status event is that the SEALDD
          connection is established.
        - RELEASED: Indicates that the SEALDD connection status event is that the SEALDD connection
          is released.
        - CLIENT_CONN_STATUS: Indicates that the SEALDD connection status event is the connection
          status of the SEALDD Client.
        - CONGESTION: Indicates that the SEALDD connection status event is congestion reporting.
        - DL_DEL_INSTRUCTIONS: Indicates that the SEALDD connection status event is the the DL data
          delivery instructions.

    TransType:
      anyOf:
        - type: string
          enum:
          - regular
          - urllc
          - mm
          - satellite
        - type: string
          description: >
            This string provides forward-compatibility with future extensions to the enumeration
            and is not used to encode content defined in the present version of this API.
      description: |
        Represents the requested transmission type.  
        Possible values are:
        - regular: Indicates that the requested transmission type is Regular transmission.
        - urllc: Indicates that the requested transmission type is URLLC transmission.
        - mm: Indicates that the requested transmission type is Multi-modal transmission.
        - satellite: Indicates that the requested transmission type is S&F Satellite transmission.

    ClientConnStatus:
      anyOf:
        - type: string
          enum:
          - REACHABLE
          - UNREACHABLE
          - SLEEPING
        - type: string
          description: >
            This string provides forward-compatibility with future extensions to the enumeration
            and is not used to encode content defined in the present version of this API.
      description: |
        Represents a SEALDD client connection status.  
        Possible values are:
        - REACHABLE: Indicates that the SEALDD Client connection status is reachable.
        - UNREACHABLE: Indicates that the SEALDD Client connection status is unreachable.
        - SLEEPING: Indicates that the SEALDD Client connection status is sleeping.

    DLDelInstructions:
      anyOf:
        - type: string
          enum:
          - ADJUST
          - PENDING_DL
          - RESUMED_DL
        - type: string
          description: >
            This string provides forward-compatibility with future extensions to the enumeration
            and is not used to encode content defined in the present version of this API.
      description: |
        Represents the DL data delivery instructions.  
        Possible values are:
        - ADJUST: Indicates that the DL data delivery instructions are to adjust data delivery.
        - PENDING_DL: Indicates that the DL data delivery instructions are to suspend data delivery
          as there is pending data delivery (e.g., feeder link is not available).
        - RESUMED_DL: Indicates that the DL data delivery instructions are to resume data delivery
          (e.g., feeder link is available).


# Data types describing alternative data types or combinations of data types:
#

