A peg family is the set of tokens that track the same reference: the ten USD tokens, the four EUR tokens, the gold pair. Grouping by peg rather than by issuer answers the operational question: which family does my invoice belong to?
Families matter for reach too: a corridor that clears in Singapore dollars is served by the SGD family regardless of which issuer's token carries it, and a family's size is a rough proxy for its liquidity and tooling depth.
A peg family is the set of tokens tracking the same reference, grouped by target rather than issuer. The family's depth matters mechanically: more tokens means more venues, more liquidity, and more wallet support for the same underlying currency. Family members are interchangeable in the sense that matters for payments, since a dollar is a dollar regardless of which USD token carries it.
Families also behave as routing surface: when a corridor clears in a currency, any family member can serve it, and the swap engine picks by price and reach rather than brand.
Family depth also shapes failure resilience. A single-token family takes that issuer's risks on whole; a ten-token family lets settlement continue through any one member's trouble, because the reference currency does not care which token carries it. Merchants enabling a family rather than a token get that redundancy for free, and buyers get wallet compatibility without coordination.
The USD family on U.CASH runs ten tokens deep, from USDT and USDC through PYUSD and FDUSD. A checkout asking for dollars accepts any of them, and the router chooses the cheapest path from whatever the buyer holds.
Thirteen peg families trade on U.CASH, ranked by size on the stablecoins ranking, each family linking to its currency page and each token to its own asset page.
Merchants should pick families, not tokens: enabling the USD family covers every dollar-pegged buyer in one setting. The peg rankings list each family with its tokens and currency page. The operational detail: family members differ in chain coverage, so enable the members that live where your buyers' wallets do. A USD buyer on Tron reaches USDT; the same buyer on Base reaches USDC or PYUSD. Treating the family as the setting and the chain as the constraint keeps the checkout list short without turning anyone away. The swap engine handles the case where a buyer holds the wrong member for their wallet's chain by routing through liquidity, so the practical instruction is simply: cover the reference currency, cover the major chains, and let routing close the gaps.
Every term behind the rails, the assets, and the settlement.