> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lerian.studio/llms.txt
> Use this file to discover all available pages before exploring further.

# What is Lerian SLC?

> Lerian's client-owned software for operating Nuclea's centralized card-settlement service (SLC) on behalf of a participant — the ASLC messaging engine, the card-arrangement roles it serves, and its standalone, multi-tenant model.

**Lerian SLC** is the client-owned software layer that operates the **Serviço de Liquidação Centralizada (SLC)**, Nuclea's centralized card-settlement messaging service, on behalf of a participant. It runs inside the institution's own regulated environment, signs with the institution's own **ICP-Brasil** certificate, and speaks the official **ASLC** message protocol to Nuclea (ISPB **29011780**) over the **RSFN**, Brazil's National Financial System Network.

Lerian SLC builds, signs, and transmits the ASLC settlement files, correlates Nuclea's returns, and tracks every operation through its settlement lifecycle by its **NUliquid**, Nuclea's settlement identifier. It is standalone, multi-tenant, and API- and event-first.

## What Lerian SLC does — and does not — do

***

* It is **standalone**. Lerian SLC settles cards on its own and depends on no other Lerian product. Midaz and Reporter can consume Lerian SLC, but Lerian SLC does not depend on them.
* The **private key never leaves the client's custody**. Lerian SLC materializes the unsigned file and delegates signing to a custody backend the client controls; Lerian never signs on the client's behalf.
* It is **multi-tenant** from the ground up. One deployment serves many participants with full isolation.

## Who it serves

***

Lerian SLC serves the roles of the Brazilian card arrangement. A single deployment can act for one or several of them.

| Role                                | What it is                                                                                    |
| ----------------------------------- | --------------------------------------------------------------------------------------------- |
| **Credenciadora** (acquirer)        | Captures card transactions from merchants and submits their settlement operations.            |
| **Subcredenciadora** (sub-acquirer) | The sub-acquirer whose representation is obligatory under Res. BCB 150/2021.                  |
| **IF Domicílio**                    | The domicile financial institution that receives settlement notices and credits the merchant. |
| **IF Liquidante**                   | The settling financial institution that funds the clearing position for a settlement cycle.   |
| **Bandeira**                        | The card scheme of the arrangement.                                                           |

## Glossary

***

| Term                                         | Meaning                                                                                                                                   |
| -------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| **Lerian SLC**                               | Lerian's client-owned software for operating Nuclea's centralized card-settlement (SLC) messaging.                                        |
| **SLC** — Serviço de Liquidação Centralizada | Nuclea's centralized settlement service for the Brazilian card arrangement.                                                               |
| **ASLC**                                     | The official Nuclea XML message layout family used by the SLC — UTF-16BE, XSD-validated.                                                  |
| **NUliquid**                                 | Nuclea's 21-position settlement identifier (an `AAAAMMDD` date prefix plus a sequence) that tracks each operation's lifecycle.            |
| **ISPB**                                     | The BACEN participant identifier; Nuclea's SLC destination is 29011780.                                                                   |
| **RSFN**                                     | Brazil's National Financial System Network, which carries SLC traffic.                                                                    |
| **ICP-Brasil**                               | The Brazilian public-key infrastructure whose certificate signs SLC files.                                                                |
| **SPB security envelope**                    | The BACEN payment-system envelope — GZIP plus an RSA/SHA-256 signature and AES-256, with a 588-byte security header — wrapping each file. |
| **Clearing cycle**                           | The settlement window over which Lerian SLC computes and reconciles positions for the IF Liquidante.                                      |

For how Lerian SLC sits alongside the other native rails and the provider interfaces, see [Native Messaging](/en/rails/native/native-messaging). The card-domain deferred-net settlement family reaches Lerian SLC relayed from [Lerian SILOC](/en/rails/native/siloc/what-is-lerian-siloc), the participant-side SILOC connectivity.