The symbol for perpetual contract is BTCUSD.
Each futures contract on Bitfex will be listed with a month code and year code, which denote its time of expiry. For instance, a contract expiring in December 2019, is listed as BTCZ19, where Z in the month code and 19 is the year code.
On Bitfex, futures contracts expire on the last Friday of the contract expiration month at 08:00:00 UTC
Below is the complete list of codes for their respective months, used in the symbol for futures contracts.
The symbol for an exchange quoted spread contract is denoted as follows: Symbol for Contract 1: Symbol for Contract 2
Eg:- Spread between Perpetual contract and December Futures will be given by BTCUSD:BTCZ19