Tokens and markets

ZooBC builds tokens and trading into the protocol. Issuing a token, sending it, swapping it and placing an order on a market are ordinary transaction types with fixed rules, so nobody writes contract code and every node applies them in the same way. Every balance of every asset counts in atomic units of 10⁻⁸: one ZBC is 100,000,000 of them, and so is one whole unit of any token.

Three kinds of asset

• ZBC is asset 0, the chain's own coin (see ZBC coin and its units). It is not a token: its balance is the account balance. No token transaction can mint or burn it, new ZBC comes only from the coinbase, and it never expires. ZBC is never burned at all (see ZBC is never burned).
• Genesis coins are tokens 1 to 14, written by block 0: ZUSD, ZEUR, ZCNY, ZBTC, ZETH, ZSOL, ZDOT, ZBNB, ZADA, ZXRP, ZTRX, ZXTZ, ZUSDC and ZUSDT. Their names say what they stand for, such as "Zoo US Dollar" for ZUSD and "Zoo Bitcoin" for ZBTC. All have 8 decimals and were created without an expiry date, so no upkeep is due for them. They are neither mintable nor redeemable: a MintToken or BurnToken on them is refused, and is a paid no-op if a block includes it anyway.
• User tokens are issued by anyone with an IssueToken transaction, and identified by the id of that transaction (see issuing a token).

Four genesis coins are bridge coins: ZBTC (bitcoin), ZETH (ether), and ZUSDC and ZUSDT (ERC-20 tokens on Ethereum). Each has a custody address fixed in the genesis, and its supply is designed to change only through bridge and wrapped coins. The other ten genesis coins have no custody address.

Using tokens

• Decimals and the step: how many of the 8 decimal places a token uses, and the step every amount must respect.
• Issuing a token: IssueToken, the rules for symbols and names, ZBC backing, and TransferToken.
• Minting and burning tokens: adding supply, and redeeming units for their share of the backing.
• Token upkeep (persistence): the free first period, and the survival payments that keep a token alive.
• Split and transact policies: split policies that share incoming money, and transact policies that refuse whole categories of transactions.

Token units can also be held in an escrow, streamed as a liquid payment or paid out by a schedule.

Trading

• Swap offers: all-or-nothing trades between any two assets.
• Markets and orders: on-chain order books, matched by every node in the same way.
• The bridge and wrapped coins: how bitcoin and ether are designed to become ZBTC and ZETH on ZooBC, and back.

Matching is part of consensus, so no operator holds the traders' funds or can reorder the book. ZooBC has no automated market-maker pools: trades happen between offers and orders that people place.

The event attestations that the bridge relies on are explained in triggers and attestations.

See also

• Transactions
• The ZBC coin and its units
• Fees
• Glossary