> ## 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 SPB?

> Lerian SPB is your direct, non-intermediated BACEN STR connector for TED-family interbank transfers and reserve-account operations over the RSFN network.

**Lerian SPB** is Lerian's own messaging connector to the **STR** (Sistema de Transferência de Reservas). The STR is the real-time gross-settlement core of the Brazilian payment system. Lerian SPB reaches the STR over the **RSFN**. The RSFN is the private national network that carries payment-system messages between participants and the Central Bank of Brazil (BACEN).

Lerian SPB gives a participant institution a direct path to BACEN. The institution sends and settles interbank and large-value wire transfers, the TED family. It also runs reserve-account operations against BACEN's settlement system. No connectivity partner sits between the institution and BACEN.

## Who it serves

***

Lerian SPB serves financial institutions that hold their own reserve and settlement account at BACEN. These institutions send TED-family transfers through the STR. They move liquidity between their reserve account and their liquidity account (Conta PI). They also query their reserve position directly through the STR.

## An operation-centric API

***

You do not hand-pick a wire code. You declare the typed roles of the parties to an operation. You name who debits, who credits, and whether each side is an institution or a client. The platform then derives the correct STR message code for you.

| Declared parties           | STR code | Movement                                                      |
| -------------------------- | -------- | ------------------------------------------------------------- |
| Institution to institution | STR0004  | Interbank transfer between two account-holding participants   |
| Non-account-holders        | STR0005  | Transfer involving parties that do not hold a reserve account |
| Client to institution      | STR0006  | A client sends to an institution                              |
| Institution to client      | STR0007  | An institution sends to a client                              |
| Client to client           | STR0008  | Transfer between two clients across institutions              |

## Settlement is asynchronous

***

The STR is a real-time gross-settlement system. Every operation settles individually against reserve balances. When you submit a transfer, the platform returns the status `ACCEPTED`. This status means the platform accepted your command for dispatch. It does not mean BACEN settled the transfer.

BACEN confirms asynchronously through a settlement reply, called the R-leg. The reply moves the operation to `CONFIRMED` or `REJECTED`. It carries BACEN's settlement fields, for example `numCtrlSTR` and `sitLancSTR`, projected verbatim.

## Money-neutrality

***

Lerian SPB is money-neutral. It forwards the amounts you declare exactly as declared and computes no balance or position of its own. The rail carries the message and settlement state. Your ledger consumer records the money movement.

## Glossary

***

| Term                                           | Meaning                                                                                                          |
| ---------------------------------------------- | ---------------------------------------------------------------------------------------------------------------- |
| **STR** — Sistema de Transferência de Reservas | BACEN's real-time gross-settlement (RTGS) system, where each operation settles individually.                     |
| **SPB** — Sistema de Pagamentos Brasileiro     | The Brazilian payment system that the STR is the settlement core of.                                             |
| **RSFN**                                       | The private national financial-system network that carries SPB messages between participants and BACEN.          |
| **TED**                                        | An electronic wire transfer settled through the STR.                                                             |
| **NUOp**                                       | 23-digit BACEN operation identifier (ISPB + date + sequence) that correlates a submitted message with its reply. |
| **ISPB**                                       | 8-digit BACEN code identifying a payment-system participant institution.                                         |
| **Conta PI / reserve-settlement account**      | The accounts an institution holds at BACEN for settlement and liquidity.                                         |
| **ICP-Brasil certificate**                     | The digital certificate used to sign outbound SPB messages.                                                      |
| **Settlement confirmation (R-leg)**            | The asynchronous BACEN reply that moves a submitted operation to `CONFIRMED` or `REJECTED`.                      |
| **STR / LPI / GEN codes**                      | Official BACEN protocol identifiers for each STR and SPB message type (for example STR0004, LPI0001, GEN0006).   |

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