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Yield_Curve__Modelled_QtyModelled Qty refers to List of possible types that describe the modelled quantity used to build the curve on which the Interpolation Method entry applies.
Available Modelled Qty types:
The discount factor is selected as the Modelled Qty
The instantaneous forward rate is selected as the Modelled Qty
The simply compounded spot rate (zero rate) is selected as the Modelled Qty