Lesson 1DE32 Acquiring Institution Identification Code: format (LLVAR up to 11n), use in routing and acquiring identificationOutlines DE32 LLVAR format up to 11 digits and acquirer ID assignment. Details routing to acquirer hosts, multi-setup handling, and interaction with routing tables.
LLVAR format and numeric constraintsAcquirer ID assignment and governanceUse of DE32 in network routingMulti-acquirer and aggregator modelsLogging DE32 for settlement mappingLesson 2DE41 Card Acceptor Terminal Identification: format (8an), terminal routing and loggingDetails DE41 8-character format, uniqueness, terminal identification across merchants/locations, routing, monitoring, and hierarchy integration.
8an format and allowed charactersTerminal ID uniqueness strategiesTerminal ID in routing and profilesTerminal ID in fraud and risk rulesTerminal inventory and lifecycle useLesson 3DE2 Primary Account Number (PAN): field name, format (LLVAR up to 19 numeric), and role in routing/BIN lookupDescribes DE2 structure, PAN lengths, LLVAR encoding, BIN routing, scheme/product/issuer identification, with masking for PCI compliance.
LLVAR encoding and PAN length limitsBIN ranges and issuer identificationPAN role in network routing decisionsPAN validation and Luhn check usageMasking PAN in logs and PCI impactsLesson 4DE38 Authorization Identification Response: format (6an), issuing bank authorization code and audit useCovers DE38 6-character format, issuer code generation, use in logs, records, disputes, and request-response consistency.
Format 6an and character constraintsIssuer code generation strategiesMapping DE38 across request/responseUse in acquirer and issuer audit logsRole in chargeback and dispute researchLesson 5DE3 Processing Code: format (6n), meaning segments (transaction type, account type), and role in transaction routingBreaks down DE3 6-digit format for transaction/account types, influencing routing, fees, and rules for various flows.
6n layout and segment meaningsCommon purchase and cash codesAccount selection and subaccount useRouting and fee rule determinationReversal and adjustment processingLesson 6DE39 Response Code: format (2an), interpretation rules and common response valuesDetails DE39 2-character format, common values, business mappings, issuer/network roles, decline/referral handling.
2an format and value rangesCommon approval and decline codesSoft declines and retry guidanceIssuer versus network generated codesMapping codes to merchant messagesLesson 7DE37 Retrieval Reference Number: format (12an), role in reconciliation, disputes, and trackingExplains DE37 12-character format, generation, uniqueness for reconciliation, disputes, cross-network tracking.
12an format and structure optionsRRN generation and uniquenessUse in reconciliation processesRole in chargebacks and disputesCross-network transaction trackingLesson 8DE14 Expiration Date: format (YYMM), card validation and decline triggersReviews DE14 YYMM format, validation, issuer checks, interactions with status, fallback, near-expiry handling.
YYMM format and parsing rulesIssuer validation of expiry dateExpired card decline scenariosNear-expiry and renewal handlingStorage and masking in host logsLesson 9DE4 Amount, Transaction: format (12n), currency handling, and settlement implicationsCovers DE4 12-digit format, minor unit scaling, DE49 alignment, impacts on holds, approvals, tips, settlement.
12n format and minor unit handlingCurrency consistency with DE49Preauthorization and hold amountsPartial approvals and tip handlingImpact on clearing and settlementLesson 10DE22 Point-of-Service Entry Mode: format (3n), values for card-present, chip, contactless, keyedExplains DE22 3-digit format for magstripe/chip/contactless/keyed entry, affecting risk, liability, strategies.
3n structure and subfield meaningsCard-present versus card-not-presentChip, contactless, and fallback codingManual and key-entered transaction flagsImpact on risk, fraud, and liabilityLesson 11DE7 Transmission Date & Time: format (MMDDhhmmss), role in logging, timeouts, and reconciliationDetails DE7 MMDDhhmmss format, time zones, host sync, roles in timeouts, duplicates, reconciliation.
MMDDhhmmss format and examplesTime zone and clock sync issuesUse in timeout and retry handlingDuplicate and late message detectionReconciliation and settlement matchingLesson 12DE49 Transaction Currency Code: format (3n, numeric ISO 4217), currency conversion and routing impactsReviews DE49 3-digit ISO 4217, links to DE4/DE51, influences on routing, FX, multi-currency setups.
3n ISO 4217 numeric codesAlignment with DE4 and DE51Multi-currency merchant scenariosFX conversion and DCC decisionsRouting based on currency fieldsLesson 13DE11 System Trace Audit Number (STAN): format (6n), uniqueness, correlation between request/responseCovers DE11 6-digit format, rules, uniqueness, linking requests/responses, traceability with RRN.
6n format and rollover behaviorSTAN generation at switch or hostUniqueness windows and collisionsCorrelation of request and responseUse in monitoring and incident traces
