Notional Ccy

Key Notional Ccy in FX Option refers to the optional denomination currency of the option's notional N entered in Notional
It expects an object of type Currency, which must equal either the base currency BASE or the quote currency QUOTE of the ratio BASE/QUOTE defined in the FX object specified in key FX.
If set to the base currency BASE, upon exercise N units of BASE are exchanged with a corresponding strike-dependent number of units of QUOTE
If set to the quote currency QUOTE, upon exercise N units of QUOTE are exchanged with a corresponding strike-dependent number of units of BASE
If omitted, the default is the underlying currency specified in Underl Ccy.

Example:

Consider a European call option referencing the FX rate USD/JPY set with N = 1,000,000
Then upon exercise the option holder will exchange:
If Notional Ccy = USD => 1,000,000 USD for the agreed strike in JPY.
If Notional Ccy = JPY => 1,000,000 JPY for the agreed strike in USD.