How Lerian SLC works

Lerian SLC runs a single settlement pipeline for every card operation: it takes an operation in, builds the ASLC file for it, has it signed under the client’s custody, transmits it to Nuclea, and correlates the returns — advancing the operation through its lifecycle by the NUliquid.

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Intake

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Operations enter Lerian SLC through two canonical modes:

• Canonical API — a REST/JSONL intake carrying operations in Lerian’s canonical shape, idempotent by external_id so a retried submission never double-settles.
• Direct ASLC XML — an upload of ready ASLC XML for callers that already produce it.

An audited pass-through mode also accepts client-pre-signed artifacts and forwards them under audit. The operation types are CREDIT, DEBIT, CANCELLATION, ANTICIPATION, and SWEEP.

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Build, sign, transmit, correlate

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Each operation flows through one pipeline:

1. Validate the operation against Nuclea’s XSDs.
2. Build the ASLC file — UTF-16BE, no BOM, up to 50,000 records per file, with automatic splitting when the count exceeds the limit.
3. Sign the file under the client’s custody (see Signing orchestration below), then apply GZIP and the SPB security envelope.
4. Transmit the file to Nuclea over REST, secured by mTLS and a per-request JWS signature.
5. Correlate Nuclea’s returns — the PRO / ERR / RET file returns and the ASLC028 status message — back to the file and its operations by file name.

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Message families

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Settlement flows

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• Credit (acquirer). Operations enter through the canonical intake, Lerian SLC builds the credit file (ASLC027), signs and transmits it, and correlates the ASLC028 status and the PRO/ERR/RET returns, advancing each operation through its NUliquid lifecycle.
• Debit and anticipation. The same intake-build-sign-transmit pipeline runs with the debit (ASLC029 / ASLC030) and anticipation (ASLC031 / ASLC034) families; status returns and NUliquid tracking mirror the credit flow.
• Cancellation. The acquirer informs a cancellation (credit ASLC060, debit ASLC064); Lerian SLC relays it to the IF Domicílio (ASLC061), receives the domicile’s processing return (ASLC062), returns the outcome to the acquirer (ASLC063 / ASLC067), and emits a cancellation-confirmed-by-domicile event carrying the NUliquid.

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IF Domicílio inbound

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Acting as the domicile institution, Lerian SLC receives credit and debit settlement notices (ASLC022 / ASLC024 / ASLC032), confirms them (ASLC023 / ASLC025 / ASLC033), and issues returns and devolutions (ASLC041 / ASLC042 / ASLC043). A webhook keyed by the NUliquid signals the credit to the merchant and carries the return evidence.

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Clearing and funding for the IF Liquidante

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For the settling institution, Lerian SLC consumes the inbound clearing preview and final (SLC0001), the SLC0002 message, and operational status (PAG0101) over the RSFN, builds the clearing position per settlement cycle, and detects D0-versus-D+1 value divergence. It raises events for preview-available, final-available, deposit-required, and deposit-deadline-approaching.

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Operation lifecycle

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Every operation advances through an 11-state lifecycle, tracked by its NUliquid. Files carry their own 10-state lifecycle, tracked per file from build through transmission and return correlation.

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Signing orchestration

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Lerian SLC materializes the unsigned ASLC XML and then delegates signing to a custody backend chosen per tenant. The private key never leaves the client’s custody, and Lerian never signs on the client’s behalf. In SaaS deployments, custody is locked to cloud KMS via client-side-wrapped key import: the client wraps and imports its own key, and the service stores only the public certificate and a key reference — never the private material.

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Transport

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Operations and files are submitted to Nuclea over REST, secured by mTLS and a per-request JWS signature (the SLC0908 / SLC0912 / SLC0915 / SLC0999 online series). The inbound returns are polled and acknowledged over the same REST channel.