A perpetual future is a contract on an underlying's price with no expiry. It
stays near the underlying's spot price through periodic funding payments
between longs and shorts. A dated future has an expiry and converges to spot
by settling at it. The two carry different risks: a dated future has to be
rolled at expiry, while a perpetual pays or earns funding for as long as it
is held. They are therefore separate kinds, and future is reserved.
New to perpetuals? The guide explains them with interactive figures.
1. Position
A position is a signed quantity of the underlying, in its base units, such as shares or tokens. It is positive when long and negative when short. The venue profile defines the base unit and how to convert the venue's own quantities into it.
max_position and min_position bound the filled position: with
min_position absent, it may go from −max_position (short) to
max_position (long), and min_position: 0 makes the allowance long-only.
Open orders do not count until they fill, so an agent that must stay under
the cap sizes its resting orders so that fills can't take it over.
2. Value
A perpetual position contributes its unrealized PnL at the venue's mark price to the account's value. The venue profile defines the mark, and whether unsettled funding is counted.