Key Currency in refers to the associated with the Yield Curve
This entry, together with the , identify the part of the nature of the corresponding Yield Curve object.
All other entries - eg conventions and market rates - represent the remaining part.
In practical terms, all Yield Curve objects in a pricing scenario must have unique pairs of Issuer and Currency
The pricing algorithm will ask - as an example - for a Yield Curve with a specific currency - eg USD - and a specific issuer - eg -.
If there exist more than one Yield Curve objects with the requested currency and issuer, the pricing will fail due to ambiguity as to which curve should be used.