Settings fields

In MesoSim, Settings controls simulation behavior (fills, slippage, commissions, margin model) and some core selection semantics (leg/expiration uniqueness).

In MesoLive:

• Most Settings.Sim.* fields are simulation-only and are ignored.
• Some Settings.Core.* concepts exist, but are often controlled by MesoLive UI rather than read from the Strategy Definition.

Settings.Core

Strategy Definition field	MesoLive support	Notes
Settings.Core.LegSelectionConstraint	Supported (different)	The Portal provides a Leg Selection dropdown in Build/Adjustments. The Strategy Definition value is not used.
Settings.Core.ExpirationSelectionConstraint	Not supported	MesoLive does not enforce the MesoSim “AbortOnReuse/AllowReuse” expiration alias uniqueness behavior.
Settings.Core.Margin	Supported	When enabled the calculated margin is shown in the position details page.
Settings.Core.Margin.Model	Not supported	Simulation-only.
Settings.Core.Margin.HouseMultiplier	Not supported	Simulation-only.
Settings.Core.Margin.RegTMode	Not supported	Simulation-only.
Settings.Core.Margin.PMConfig	Not supported	Simulation-only.

LegSelectionConstraint (Core)

MesoLive supports the concept of leg uniqueness during selection, but:

• It is selected in the Portal UI during Build/Adjustments.
• Only FullyUnique and UniqueInPosition are currently offered in the UI (MesoSim also supports None).

ExpirationSelectionConstraint

MesoSim can enforce that expiration aliases resolve to distinct targets (when AbortOnReuse is used).

MesoLive currently resolves each expiration alias independently and does not enforce that two aliases can’t land on the same expiration.

Workaround: ensure your expiration aliases cannot resolve to the same contract by using distinct DTE targets and/or Min/Max constraints and/or root filters.

Settings.Sim (simulation-only)

Strategy Definition field	MesoLive support	Notes
Settings.Sim.FillModel	Ignored	Live trading uses broker fills and Operator order handling; paper trading uses user-entered fills.
Settings.Sim.SlippageAmt	Ignored	Simulation-only.
Settings.Sim.Commission	Ignored	Simulation-only. Paper trading commissions are configured per paper account in MesoLive.
Settings.Sim.PositionMonitor	Ignored	Simulation-only.
Settings.Sim.TearsheetGeneration	Ignored	Simulation-only.

Settings.User

Strategy Definition field	MesoLive support	Notes
Settings.User	Ignored	Not currently used by MesoLive.