Really naive question..... but i have not seen this addressed anywhere...Thank you in advance for any repliesExampleclient buys @ expiry digi EUR Call, k=1.40, Notional=1mio EURif Spot is above 1.40, what is the payout?[a] 1 USD per EUR...in which case the payout=1mio USD? or payout=Notional in EUR, so in this example it is 1mio EURIn other words is the set up of a At Expiry Digital Payout the same as an One-Touch(with the exception of when the barrier is observed)? If yes this would implychoice above.Looking at the replication of the digi with the call spread i would say it is [a]I would think that to price using a call spread replication, you would probably need toreplicate with quadratic options.

the payout is what you specify the notional is. if it's 1 EUR, as is the default for EURUSD digitals, then 1 EUR is the payout. you could have specified 1 USD, in which case the payout would be 1 USD.