"spsPercentOfEquity (=2) - size expressed as percent of portfolio-level equity (size must be from ..100 (for regular accounts) or .1000 for margin accounts)"

Question: If I have Futures Mode enabled, Margin deposit specified etc and want to limit exposure e.g. to 3% of equity, what does .1000 above refer to?
Should one specify a 3% equity position size as :
a) 3 or
b) 0.03 ?

I think you're interpreting it the other way around and taken by the decimal. .1000 is more like from ..100 as in upto 100.

if SetPositionSize( 50, spsPercentOfEquity ); this is 50% of Portf Eq
Now mathematically, in % terms, for regular accounts.
100 means all the available Portfolio Equity or PE in context of this post for easy , or 100%

In Futures mode, if your MarginRequirement is 10%
then you enter 10 in Margin Requirement textbox in settings.
Your max position size can be 10 times your PE = leverage = (100 x 10)
or SetPositionSize( 1000, spsPercentOfEquity );

In your whole post, you fail to mention the Margin Requirement and use etc forcing others to assume,
lets says its 10%

so now you don't use 3 or 0.03 but a tenth of 3% that is 0.3

@Tomasz I'm actually coming from there (h_futbacktest.html) and that's what I was interpreting the .1000
is the interpretation wrong with the tenth ?

Futures mode check box in the settings page (underscored with green line in the picture above) is the key to backtesting futures. It instructs backtester to use margin deposit and point value in calculations.

Ok, so still need to put 2 and 2 together with that 1000.

Ok, well answering the question myself, it would be the MarginDeposit and assuming that RoundLotSize=1, then we'd have it as 3 or 3% of PE.