Sparse SABR Params

Key _Sparse SABR Params in Vol Curve refers to the set with the calibrated SABR sparse parameters as returned by QuantLib, represented as an object of type Set

Note, this is generated as soon as the contents of a Vol Curve object are displayed.
For efficiency reasons this is never generated during the creation (but not display) of a Vol Curve object.

Expects an object of type Set representing a table consisting of 10 columns that may be arranged in any order.
Each column is uniquely identified by the text label at its top cell that is specially formatted and known as the column's title

The following titles apply in the table here:
#SwaptionTenor
#SwaptionExpiry
#Alpha
#Beta
#Nu
#Rho
#AtmFwd
#RMS
#MaxError
#OptimMethod

Note this key is prefixed by _, which indicates it is regarded as a read-only part of the object's data and therefore its associated value cannot be edited.
For that reason it does not appear as part of the input data.
It carries informational only value for the user and appears as part of its contents.
Also it completely depends on the remaining object contents and therefore is never part of the exported object's data.