A market reference built from the market, not one order book.
According to Sumcoin's published methodology, the SUM reference price follows the top 100 cryptocurrencies by global market capitalization and draws from more than 600 data points in near real time.
The index tracks the leading cryptocurrencies by global market capitalization.
The broader market inputs are aggregated into the Sumcoin Index reference value.
Wallets, counterparties and market tools can use the resulting SUM rate as a common reference point.
Peer-to-peer money still needs a way for two people to discuss value.
A wallet can transfer coins without an exchange, but two people still need a way to decide what those coins are worth. Sumcoin's answer is to separate that reference-price function from any single SUM trading venue.
This does not mean every counterparty must transact at exactly the index rate. People can still negotiate. The index supplies a common starting point that does not require both parties to use the same centralized exchange.