# Payment QR modes — UI82.1

Default: **With address**. The buyer may switch to **With amount**. Copy address and copy amount remain available.
USDT/TRC20 uses `ADDRESS?amount=DECIMAL_USDT` with the exact server-generated final PayAmount, matching the payload decoded from the merchant's NOWPayments USDT/TRX With amount screenshot (24.976996 USDT). No `tron:` prefix, TRX sun conversion, contract, order ID or additional query fields are added. This format does not explicitly encode the asset/network; verify the wallet displays USDT on TRON and the exact amount before paying. The merchant reported a successful NOWPayments test; this release does not claim independent OKX/Binance acceptance.
Payment precision follows MochiPay MP_Currency.MatchDecimals and the saved PayAmount. The current source defaults are USDT/USDC4, BTC/ETH8 and SOL6; do not copy NOWPayments' six-place amount setting. QR code never rounds, pads or chooses order precision. The six/eight/eighteen/nine limits below are protocol/token unit guards, separate from matching precision.
BTC uses bitcoin: URI (8 decimals), ETH uses ERC-681 on Ethereum mainnet chain1 (18 decimals), native USDC on Ethereum uses ERC-681 transfer (6 decimals), SOL uses Solana Pay (9 decimals). Amounts are decimal strings, never floating-point values. Precision beyond the asset limit disables amount mode; no rounding is applied. Invalid/unrecognized asset, network, address or amount also disables amount mode with a translated explanation.
Switching QR modes is local display only, with no new order, API secret, wallet permission, transaction or payment-status change. New orders reset to address mode. Language changes retain the values. The received amount must equal the exact amount shown; some exchanges deduct withdrawal fees from the amount entered.
Update gateway frontend assets in place and clear the store cache; preserve settings and existing order bindings. HPP requires WEB82.1. Merchant installation instructions stay English; buyer choices/explanations support multiple languages, including English, Chinese, Spanish, and more. No native-store installation or live transfer was performed in this source release.
