In addition to the outright contracts, Coinbase Derivatives also lists calendar spreads for each product. Calendar spread contracts involve the buying of one expiry and selling of another expiry of the same product with a single order. Coinbase Derivatives futures calendar spreads follow the reverse spread convention (i.e buying the calendar spread refers to buying the far month of the calendar spread, selling the calendar spread refers to selling the far month of the calendar spread).
Example: Buy 1 lot of BTIX24-BTIZ24 refers to buying 1 lot of BTIZ24 and selling 1 lot of BTIX24.