Display Currency

Overview

Display Currency controls presentation. A merchant can show an order as 100 USD or 90 EUR even when the payer ultimately sends BTC, USDT, or another accepted asset. The displayed unit helps users understand price without changing the blockchain transaction.

It should be separated from Pay Currency, which is the asset the payer transfers, and from Quote Currency, which identifies the unit in an exchange-rate pair. Conflating these fields creates ambiguous invoices and reconciliation errors.

The interface should show the displayed amount, corresponding crypto amount, network, rate, and Quote Expiration. If the quote expires, the display must be refreshed rather than silently accepting an outdated conversion.

Precision and formatting are currency-specific. Fiat currencies can have different decimal conventions, while crypto assets can require many fractional digits. Rounding should be consistent with the actual expected amount and amount-tolerance rule.

Display currency also affects localization but should not be used as evidence of legal settlement or tax denomination. Reports must retain the original display amount and the actual on-chain amount separately so customer-facing presentation does not overwrite financial facts.

A localized display can also introduce conversion layers. For example, a merchant may report in EUR, display in GBP, and request USDT. The interface must identify which value is authoritative for the order and how often the displayed estimate refreshes. Accessibility and localization should preserve decimal separators and currency symbols without changing the underlying numeric value.

Display changes should be tested against cached quotes, language settings, and mobile layouts. The payer must never see a rounded presentation that conflicts with the exact amount encoded in the QR or payment URI.