But mostly don't.

Who is still in the trenches for one of the last remaining big firms?  I haven't been since early 2001.

I remember having to code these in 3 days from scratch when they exploded on the scene. I think I got an hours sleep then.

We went with implementing them as zero premium options (when booked) that settle with a positive or negative premium, depending on the traders P(L).

Pure casino gambling...

NDFs.

"A non-deliverable forward is an FX Forward for which the physical exchange of currency at expiry is replaced by settlement between counterparties of the net profit / loss on the contract, calculated off the prevailing spot rate two days prior to settlement."