Used to specify the differential price when reporting the individual leg of a spread trade. Both leg price and differential price may be provided on such a report. Note that MultiLegReportingType(442) will be set to 2 (Individual leg of a multi-leg security) in this case.
Also used in pricing Trade at Settlement (TAS) and Trade At Marker (TAM) contracts for which the value is the negotiated currency offset either at settlement (TAS) or at time specified in the product definition (TAM). The final contract price is specified in LastPx(31).