Montran Instant Payments Gateway

openapi: 3.1.0
info:
  title: Montran Instant Payments Gateway API
  description: >-
    The Montran Instant Payments Gateway (IPG) enables participants in an instant
    payments ecosystem to support high volumes of instant payments in a high
    availability 24x7 environment. The gateway complies with PSD2 Open API
    requirements and offers a unified API based on the ISO 20022 messaging
    standard. It supports Payment Initiation Service Providers (PISP) for
    payment initiation and Account Information Service Providers (AISP) for
    account information access. The system supports credit transfers, request
    to pay, bulk payments, and QR code-based instant payment initiation. It
    natively processes ISO 20022 pacs, pain, and camt messages and supports
    active-active deployment across clouds.
  version: 1.0.0
  contact:
    name: Montran Corporation
    url: https://www.montran.com/contact-us/
  license:
    name: Proprietary
    url: https://www.montran.com/terms-conditions/
  x-logo:
    url: https://www.montran.com/logo.png
externalDocs:
  description: Montran Instant Payments Gateway Documentation
  url: https://www.montran.com/solutions/instant-payments-gateway/
servers:
  - url: https://api.montran.com/ipg/v1
    description: Montran Instant Payments Gateway API Server
tags:
  - name: Account Information
    description: >-
      PSD2-compliant account information operations for AISP integration.
      Provides account details, balances, and transaction history.
  - name: Consent
    description: PSD2 consent management for AISP and PISP access
  - name: Instant Payments
    description: >-
      Real-time instant payment processing with guaranteed end-to-end latency
      of a few seconds
  - name: Payment Initiation
    description: >-
      PSD2-compliant payment initiation operations for PISP integration.
      Supports instant credit transfers and request-to-pay flows.
  - name: Payment Status
    description: Real-time payment status inquiry and notification operations
  - name: Request to Pay
    description: Request-to-pay initiation and management operations
paths:
  /consents:
    post:
      operationId: createConsent
      summary: Montran Create a PSD2 consent
      description: >-
        Creates a new PSD2 consent for account access (AISP) or payment
        initiation (PISP). The consent must be authorized by the payment
        service user (PSU) before it can be used. Supports Strong Customer
        Authentication (SCA) flows as required by PSD2.
      tags:
        - Consent
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/ConsentRequest'
      responses:
        '201':
          description: Consent successfully created, pending PSU authorization
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ConsentResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /consents/{consentId}:
    get:
      operationId: getConsent
      summary: Montran Get consent status
      description: >-
        Retrieves the current status and details of a PSD2 consent. Used to
        check whether the consent has been authorized by the PSU and remains
        valid for use.
      tags:
        - Consent
      parameters:
        - $ref: '#/components/parameters/ConsentIdParam'
      responses:
        '200':
          description: Successfully retrieved consent details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ConsentResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
    delete:
      operationId: revokeConsent
      summary: Montran Revoke a consent
      description: >-
        Revokes an existing PSD2 consent. Once revoked, the consent can no
        longer be used for account access or payment initiation.
      tags:
        - Consent
      parameters:
        - $ref: '#/components/parameters/ConsentIdParam'
      responses:
        '204':
          description: Consent successfully revoked
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/instant:
    post:
      operationId: initiateInstantPayment
      summary: Montran Initiate an instant payment
      description: >-
        Initiates a real-time instant payment with guaranteed end-to-end
        processing latency of a few seconds. The payment is processed using
        ISO 20022 pacs.008 FIToFICustomerCreditTransfer messaging. Supports
        credit transfers across instant payment schemes. Returns the payment
        status synchronously, including confirmation or rejection.
      tags:
        - Instant Payments
        - Payment Initiation
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/InstantPaymentRequest'
      responses:
        '201':
          description: Instant payment successfully processed
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InstantPaymentResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '500':
          $ref: '#/components/responses/InternalServerError'
        '503':
          description: Service temporarily unavailable
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /payments/instant/{paymentId}:
    get:
      operationId: getInstantPayment
      summary: Montran Get instant payment details
      description: >-
        Retrieves the full details and current status of a specific instant
        payment. Returns ISO 20022 pacs.002 status information including
        acceptance or rejection reason codes.
      tags:
        - Instant Payments
        - Payment Status
      parameters:
        - $ref: '#/components/parameters/PaymentIdParam'
      responses:
        '200':
          description: Successfully retrieved instant payment details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/InstantPaymentDetail'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/instant/{paymentId}/return:
    post:
      operationId: returnInstantPayment
      summary: Montran Return an instant payment
      description: >-
        Initiates the return of a previously received instant payment. Uses
        ISO 20022 pacs.004 PaymentReturn messaging. The return must specify a
        valid reason code.
      tags:
        - Instant Payments
      parameters:
        - $ref: '#/components/parameters/PaymentIdParam'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/PaymentReturnRequest'
      responses:
        '200':
          description: Payment return successfully initiated
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentReturnResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '409':
          description: Payment cannot be returned in its current state
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/credit-transfer:
    post:
      operationId: initiateCreditTransfer
      summary: Montran Initiate a PISP credit transfer
      description: >-
        Initiates a credit transfer payment on behalf of a Payment Service
        User (PSU) as a Payment Initiation Service Provider (PISP) under
        PSD2. Requires valid PSU consent. Uses ISO 20022 pain.001
        CustomerCreditTransferInitiation format.
      tags:
        - Payment Initiation
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreditTransferRequest'
      responses:
        '201':
          description: Credit transfer successfully initiated
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentInitiationResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/request-to-pay:
    post:
      operationId: initiateRequestToPay
      summary: Montran Initiate a request to pay
      description: >-
        Initiates a request-to-pay (R2P) message to request payment from a
        debtor. The debtor receives the request and can accept or reject it.
        Supports person-to-person, person-to-merchant, and business-to-business
        use cases. Uses ISO 20022 pain.013 CreditorPaymentActivationRequest.
      tags:
        - Request to Pay
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/RequestToPayRequest'
      responses:
        '201':
          description: Request to pay successfully created
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/RequestToPayResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/request-to-pay/{requestId}:
    get:
      operationId: getRequestToPay
      summary: Montran Get request-to-pay details
      description: >-
        Retrieves the details and current status of a request-to-pay. Shows
        whether the request has been accepted, rejected, or is still pending.
      tags:
        - Request to Pay
      parameters:
        - name: requestId
          in: path
          required: true
          description: Unique identifier of the request to pay
          schema:
            type: string
      responses:
        '200':
          description: Successfully retrieved request-to-pay details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/RequestToPayDetail'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/bulk:
    post:
      operationId: submitBulkPayment
      summary: Montran Submit a bulk payment
      description: >-
        Submits a batch of instant payments for processing. Each payment in
        the batch is processed individually in real-time. Supports high-volume
        use cases such as salary payments and batch collections.
      tags:
        - Instant Payments
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/BulkPaymentRequest'
      responses:
        '202':
          description: Bulk payment accepted for processing
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BulkPaymentResponse'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '422':
          $ref: '#/components/responses/UnprocessableEntity'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /accounts:
    get:
      operationId: listAccounts
      summary: Montran List accessible accounts (AISP)
      description: >-
        Retrieves a list of payment accounts accessible to the Account
        Information Service Provider (AISP) under an authorized PSD2 consent.
        Provides account identification, type, currency, and basic balance
        information.
      tags:
        - Account Information
      parameters:
        - name: consentId
          in: query
          required: true
          description: PSD2 consent identifier authorizing access
          schema:
            type: string
      responses:
        '200':
          description: Successfully retrieved list of accounts
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/AccountList'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /accounts/{accountId}:
    get:
      operationId: getAccountDetails
      summary: Montran Get account details (AISP)
      description: >-
        Retrieves detailed information about a specific payment account
        including account holder name, IBAN, currency, and product type.
        Requires valid PSD2 AISP consent.
      tags:
        - Account Information
      parameters:
        - $ref: '#/components/parameters/AccountIdParam'
        - name: consentId
          in: query
          required: true
          description: PSD2 consent identifier
          schema:
            type: string
      responses:
        '200':
          description: Successfully retrieved account details
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/AccountDetail'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /accounts/{accountId}/balances:
    get:
      operationId: getAccountBalances
      summary: Montran Get account balances (AISP)
      description: >-
        Retrieves the current balances for a specific payment account.
        Returns available balance, booked balance, and expected balance.
        Requires valid PSD2 AISP consent.
      tags:
        - Account Information
      parameters:
        - $ref: '#/components/parameters/AccountIdParam'
        - name: consentId
          in: query
          required: true
          description: PSD2 consent identifier
          schema:
            type: string
      responses:
        '200':
          description: Successfully retrieved account balances
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/AccountBalances'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /accounts/{accountId}/transactions:
    get:
      operationId: getAccountTransactions
      summary: Montran Get account transactions (AISP)
      description: >-
        Retrieves a list of transactions for a specific payment account.
        Supports filtering by date range, booking status, and amount.
        Requires valid PSD2 AISP consent.
      tags:
        - Account Information
      parameters:
        - $ref: '#/components/parameters/AccountIdParam'
        - name: consentId
          in: query
          required: true
          description: PSD2 consent identifier
          schema:
            type: string
        - name: dateFrom
          in: query
          description: Start date for transaction filter (ISO 8601)
          schema:
            type: string
            format: date
        - name: dateTo
          in: query
          description: End date for transaction filter (ISO 8601)
          schema:
            type: string
            format: date
        - name: bookingStatus
          in: query
          description: Filter by booking status
          schema:
            type: string
            enum:
              - booked
              - pending
              - both
        - $ref: '#/components/parameters/PageParam'
        - $ref: '#/components/parameters/PageSizeParam'
      responses:
        '200':
          description: Successfully retrieved transactions
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TransactionList'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /accounts/{accountId}/verification:
    post:
      operationId: verifyAccountBalance
      summary: Montran Verify account balance sufficiency
      description: >-
        Performs a balance sufficiency check on a payment account. Returns
        whether the account has sufficient funds for the specified amount
        without disclosing the actual balance. Used for pre-payment
        validation.
      tags:
        - Account Information
      parameters:
        - $ref: '#/components/parameters/AccountIdParam'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/BalanceVerificationRequest'
      responses:
        '200':
          description: Balance verification result
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/BalanceVerificationResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
  /payments/{paymentId}/status:
    get:
      operationId: getPaymentStatus
      summary: Montran Get payment status
      description: >-
        Retrieves the real-time processing status of a payment. Returns
        ISO 20022 pacs.002 status codes including acceptance, rejection,
        or settlement confirmation.
      tags:
        - Payment Status
      parameters:
        - $ref: '#/components/parameters/PaymentIdParam'
      responses:
        '200':
          description: Successfully retrieved payment status
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PaymentStatusResponse'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '500':
          $ref: '#/components/responses/InternalServerError'
components:
  securitySchemes:
    oauth2:
      type: oauth2
      description: OAuth 2.0 authorization for PSD2 AISP/PISP access
      flows:
        authorizationCode:
          authorizationUrl: https://auth.montran.com/oauth2/authorize
          tokenUrl: https://auth.montran.com/oauth2/token
          scopes:
            aisp: Account Information Service Provider access
            pisp: Payment Initiation Service Provider access
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: JWT bearer token authentication
  parameters:
    PaymentIdParam:
      name: paymentId
      in: path
      required: true
      description: Unique identifier of the payment
      schema:
        type: string
    ConsentIdParam:
      name: consentId
      in: path
      required: true
      description: Unique identifier of the PSD2 consent
      schema:
        type: string
    AccountIdParam:
      name: accountId
      in: path
      required: true
      description: Unique identifier of the payment account
      schema:
        type: string
    PageParam:
      name: page
      in: query
      description: Page number for pagination
      schema:
        type: integer
        minimum: 1
        default: 1
    PageSizeParam:
      name: pageSize
      in: query
      description: Number of items per page
      schema:
        type: integer
        minimum: 1
        maximum: 100
        default: 20
  schemas:
    ConsentRequest:
      type: object
      description: PSD2 consent creation request
      required:
        - consentType
        - psuId
      properties:
        consentType:
          type: string
          description: Type of PSD2 consent
          enum:
            - AISP
            - PISP
        psuId:
          type: string
          description: Payment Service User identifier
        accountIds:
          type: array
          description: List of account IDs for AISP consent
          items:
            type: string
        validUntil:
          type: string
          format: date
          description: Expiration date of the consent
        frequencyPerDay:
          type: integer
          description: Maximum number of access requests per day
          minimum: 1
        recurringIndicator:
          type: boolean
          description: Whether the consent is for recurring access
    ConsentResponse:
      type: object
      description: PSD2 consent details
      properties:
        consentId:
          type: string
          description: Unique consent identifier
        consentType:
          type: string
          enum:
            - AISP
            - PISP
        status:
          type: string
          description: Consent status
          enum:
            - received
            - valid
            - rejected
            - expired
            - revokedByPsu
            - terminatedByTpp
        scaRedirectUrl:
          type: string
          format: uri
          description: URL for SCA redirect flow
        validUntil:
          type: string
          format: date
        createdAt:
          type: string
          format: date-time
    InstantPaymentRequest:
      type: object
      description: >-
        Instant payment initiation request using ISO 20022 pacs.008
        FIToFICustomerCreditTransfer structure
      required:
        - debtorAccount
        - creditorAccount
        - amount
        - currency
      properties:
        messageId:
          type: string
          description: Unique message identification
        endToEndId:
          type: string
          description: End-to-end identification assigned by the initiating party
        transactionId:
          type: string
          description: Unique transaction identification
        debtorName:
          type: string
          description: Name of the debtor (payer)
        debtorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        debtorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        creditorName:
          type: string
          description: Name of the creditor (payee)
        creditorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        creditorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        amount:
          type: number
          format: double
          description: Payment amount
          minimum: 0.01
        currency:
          type: string
          description: ISO 4217 currency code
          pattern: ^[A-Z]{3}$
        remittanceInformation:
          type: string
          description: Remittance information or payment reference
        purpose:
          type: string
          description: Purpose code for the payment
        chargeBearer:
          type: string
          enum:
            - SLEV
    InstantPaymentResponse:
      type: object
      description: Response for an instant payment including real-time status
      properties:
        paymentId:
          type: string
          description: Unique payment identifier
        messageId:
          type: string
          description: Message identification
        endToEndId:
          type: string
          description: End-to-end identification
        transactionId:
          type: string
          description: Transaction identification
        status:
          type: string
          description: Payment processing status (ISO 20022 status codes)
          enum:
            - ACCP
            - ACSC
            - ACSP
            - RJCT
        reasonCode:
          type: string
          description: Rejection reason code if status is RJCT
        settlementDate:
          type: string
          format: date
          description: Settlement date
        acceptanceDateTime:
          type: string
          format: date-time
          description: Timestamp of payment acceptance
    InstantPaymentDetail:
      type: object
      description: Full instant payment details
      properties:
        paymentId:
          type: string
        messageId:
          type: string
        endToEndId:
          type: string
        transactionId:
          type: string
        status:
          type: string
          enum:
            - ACCP
            - ACSC
            - ACSP
            - RJCT
            - CANC
            - RTND
        debtorName:
          type: string
        debtorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        debtorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        creditorName:
          type: string
        creditorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        creditorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        amount:
          type: number
          format: double
        currency:
          type: string
        remittanceInformation:
          type: string
        reasonCode:
          type: string
        settlementDate:
          type: string
          format: date
        acceptanceDateTime:
          type: string
          format: date-time
        createdAt:
          type: string
          format: date-time
    CreditTransferRequest:
      type: object
      description: >-
        PSD2 PISP credit transfer request using ISO 20022 pain.001
        CustomerCreditTransferInitiation
      required:
        - consentId
        - debtorAccount
        - creditorAccount
        - amount
        - currency
      properties:
        consentId:
          type: string
          description: PSD2 consent identifier authorizing the payment
        debtorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        creditorName:
          type: string
          description: Name of the creditor
        creditorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        creditorAgent:
          $ref: '#/components/schemas/FinancialInstitution'
        amount:
          type: number
          format: double
          description: Payment amount
          minimum: 0.01
        currency:
          type: string
          description: ISO 4217 currency code
          pattern: ^[A-Z]{3}$
        endToEndId:
          type: string
          description: End-to-end identification
        remittanceInformation:
          type: string
          description: Remittance information
    PaymentInitiationResponse:
      type: object
      description: Response for a PISP-initiated payment
      properties:
        paymentId:
          type: string
          description: Unique payment identifier
        status:
          type: string
          description: Payment initiation status
          enum:
            - RCVD
            - PDNG
            - ACCP
            - RJCT
        scaRedirectUrl:
          type: string
          format: uri
          description: URL for SCA redirect if required
        createdAt:
          type: string
          format: date-time
    RequestToPayRequest:
      type: object
      description: >-
        Request-to-pay initiation using ISO 20022 pain.013
        CreditorPaymentActivationRequest
      required:
        - creditorAccount
        - debtorAccount
        - amount
        - currency
      properties:
        messageId:
          type: string
          description: Unique message identification
        creditorName:
          type: string
          description: Name of the creditor (requester)
        creditorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        debtorName:
          type: string
          description: Name of the debtor (payer)
        debtorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        amount:
          type: number
          format: double
          description: Requested payment amount
          minimum: 0.01
        currency:
          type: string
          description: ISO 4217 currency code
          pattern: ^[A-Z]{3}$
        expiryDate:
          type: string
          format: date-time
          description: Expiry date/time for the request
        remittanceInformation:
          type: string
          description: Remittance information
        purpose:
          type: string
          description: Purpose of the request
    RequestToPayResponse:
      type: object
      description: Response for a request-to-pay initiation
      properties:
        requestId:
          type: string
          description: Unique request-to-pay identifier
        status:
          type: string
          enum:
            - CREATED
            - SENT
            - REJECTED
        createdAt:
          type: string
          format: date-time
    RequestToPayDetail:
      type: object
      description: Full request-to-pay details with status
      properties:
        requestId:
          type: string
        messageId:
          type: string
        status:
          type: string
          enum:
            - CREATED
            - SENT
            - ACCEPTED
            - REJECTED
            - EXPIRED
            - CANCELLED
        creditorName:
          type: string
        creditorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        debtorName:
          type: string
        debtorAccount:
          $ref: '#/components/schemas/AccountIdentification'
        amount:
          type: number
          format: double
        currency:
          type: string
        expiryDate:
          type: string
          format: date-time
        resultingPaymentId:
          type: string
          description: Payment ID if the request was accepted and payment initiated
        createdAt:
          type: string
          format: date-time
        updatedAt:
          type: string
          format: date-time
    PaymentReturnRequest:
      type: object
      description: >-
        Payment return request using ISO 20022 pacs.004 PaymentReturn
      required:
        - reasonCode
      properties:
        reasonCode:
          type: string
          description: Return reason code
          enum:
            - AC01
            - AC04
            - AC06
            - AG01
            - AM05
            - BE04
            - DNOR
            - FOCR
            - MD01
            - MS02
            - RR01
        additionalInformation:
          type: string
          description: Additional return reason information
    PaymentReturnResponse:
      type: object
      description: Response for a payment return
      properties:
        returnId:
          type: string
          description: Unique return identifier

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# Full source: https://raw.githubusercontent.com/api-evangelist/montran/refs/heads/main/openapi/montran-instant-payments-gateway-openapi.yml