Found an old copy of the docs, it doesn't have everything but it's good enough:
(Float) Interest that has accumulated but has not been paid or charged.
Backtest value: 0
(Float) Equity with loan value less the initial margin requirement.
Backtest value: context.portfolio.cash
(Float)
IB Cash Account: Minimum (Equity with Loan Value, Previous Day Equity with Loan Value)-Initial Margin.
IB Margin Account: Available Funds * 4.
Backtest value: Infinity
(Float) Excess liquidity as a percentage of net liquidation.
Backtest value: context.portfolio.cash / context.portfolio.portfolio_value
(Float) The number of open/close trades a user can place before pattern day trading is detected.
Backtest value: Infinity
(Float)
IB Cash Account: Settled Cash.
IB Margin Account: Total cash value + stock value + bond value + (non-U.S. & Canada securities options value).
Backtest value: context.portfolio.portfolio_value
(Float) Equity with loan value less the maintenance margin.
Backtest value: context.portfolio.cash
(Float) The minimum portion of a new security purchase that an investor must pay for in cash.
Backtest value: 0
(Float) Gross position value divided by net liquidation.
Backtest value: (long value + abs(short_value)) / context.portfolio.portfolio_value
(Float) The amount of equity which must be maintained in order to continue holding a position.
Backtest value: 0
(Float) The default value is also used for live trading.
Backtest value: Net exposure value divided by net liquidation.
(Float) Total cash, stock, securities options, bond, and fund value.
Backtest value: context.portfolio.portfolio_value
(Float)
IB Cash Account: Settled Cash.
IB Margin Account: Total cash value + stock value + bond value + (non-U.S. & Canada securities options value).
Backtest value: context.portfolio.cash
(Float) The margin requirement calculated under US Regulation T rules.
Backtest value: Infinity
(Float) Cash recognized at the time of settlement less purchases at the time of trade, commissions, taxes, and fees.
Backtest value: context.portfolio.cash
(Float) The sum of the absolute value of all stock and equity option positions.
Backtest value: context.portfolio.positions_value