> ## 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 SILOC?

> Lerian's participant-side connectivity to SILOC, BACEN's deferred multilateral net settlement system operated by Nuclea — the gateway connection, card-domain settlement relay, and participant and certificate administration.

**Lerian SILOC** is a financial institution's participant-side connectivity to **SILOC**, the deferred multilateral net settlement system of the Central Bank of Brazil (BACEN), operated by the clearinghouse **Nuclea**. SILOC nets many interbank credit-order transactions and settles only the resulting **net position** on Nuclea's settlement account at the **STR**, BACEN's Reserve Transfer System. Two products settle through SILOC: **boleto** (Cobrança) and **cards**.

Lerian SILOC gives an institution one direct path to SILOC. It owns the single messaging-gateway connection to Nuclea's SILOC over the national financial-system network, relays the card-domain settlement traffic to **Lerian SLC** (Lerian's card-settlement service), and administers participants, regulated certificates, and settlement-coverage capabilities.

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

***

Lerian SILOC carries messages and administers the participant's connection. It holds **no** position and executes **no** transfer.

* The netting and the final settlement of the net position are performed by SILOC and Nuclea, not by Lerian SILOC.
* The STR deposit leg — the monetary settlement at BACEN — is executed by the separate STR rail, [Lerian SPB](/en/rails/native/spb/what-is-lerian-spb), not by SILOC.
* Lerian SILOC computes no cycle and performs no monetary arithmetic. It routes bytes and emits facts.

The service is single-institution: it connects one financial institution to SILOC, with no multi-tenancy.

## Who it serves

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Lerian SILOC serves financial institutions that are **direct or indirect SILOC participants** under their own **ISPB**. The service opens and maintains their gateway connection to Nuclea, relays the card-domain settlement family to Lerian SLC, keeps a directory of the participants it settles for, and holds the regulated certificate references the connection requires.

## Glossary

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| Term                                                                                              | Meaning                                                                                                                               |
| ------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------- |
| **Lerian SILOC**                                                                                  | A financial institution's native, participant-side connectivity to SILOC — gateway connection, card-domain relay, and administration. |
| **SILOC** — Sistema de Liquidação Diferida das Transferências Interbancárias de Ordens de Crédito | BACEN's deferred multilateral net settlement system, operated by Nuclea.                                                              |
| **Nuclea**                                                                                        | The clearinghouse that operates SILOC and settles its net position at the STR/BACEN.                                                  |
| **LDL** — Liquidação Diferida Líquida                                                             | Deferred multilateral net settlement, SILOC's settlement model.                                                                       |
| **Deferred net settlement**                                                                       | Settling only the net position of many transactions at fixed daily cycle times, rather than each transaction individually.            |
| **STR** — Sistema de Transferência de Reservas                                                    | BACEN's Reserve Transfer System, where SILOC's net position is finally settled; the deposit leg is executed by the separate STR rail. |
| **Participant**                                                                                   | An institution in SILOC, classified as direct, indirect, or settling institution.                                                     |
| **ISPB**                                                                                          | BACEN's 8-digit participant identifier.                                                                                               |
| **NUOp** — Número Único da Operação                                                               | BACEN's globally unique per-operation identifier, used as the deduplication key.                                                      |
| **Boleto (Cobrança) and Cards**                                                                   | The two products that settle through SILOC; card settlement is handled by the sibling Lerian SLC service.                             |

For how Lerian SILOC sits alongside the other native rails and the provider interfaces, see [Native Messaging](/en/rails/native/native-messaging).