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

# Exchange rates

> Rates only matter at the edges, and they are locked per quote.

## Everything onchain is AUSD

Collateral, debt, repayments and sends are all in AUSD. Because collateral and debt share a currency, the collateral ratio cannot drift with exchange rates, and the contract needs no oracle.

## Rates live offchain, at the edges

A rate is used only when money crosses into or out of AUSD: a top-up, a settlement, a cash-out. Each needs a **quote**, locked for **60 seconds**.

| Pair | Used for |
| - | - |
| `USD/MYR` | Top-ups and settlements in ringgit |
| `USD/IDR` | Top-ups, settlements and cash-outs in rupiah |

AUSD counts as USD.

## Rounding

Conversions round to the currency's smallest unit (sen, rupiah, or a millionth of an AUSD), always in the user's disfavour by at most one unit, so the treasury never pays out more than it took in:

| Operation | Rounds |
| - | - |
| Top-up: fiat → AUSD credited | Down |
| Settlement: AUSD owed → fiat charged | Up |
| Cash-out: AUSD → fiat paid | Down |

## Who carries the FX risk

The borrower. Debt is fixed in AUSD, so if the ringgit weakens between drawing and settling, more ringgit is needed. The settle screen shows the amount before you pay.

## Rate source

On testnet: public ECB reference rates. In production: the payment partner's rate.


This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.