Bigfoot I have signed quite a few NDAs in my life, There were different "types". When prototyping for BAE Systems we signed an NDA and after the product was done we received a disclosure clearance from the company. I thought it was odd but they send them to their vendors at the close of a project.
I have signed an NDA that said if I quit working for a company that had a unique process for embedding objects in acrylic. That I would not work in the field of casting acrylic for 7 years following the termination of my employment.
And I have signed open ended NDAs that 20 years later I still can not talk about.
It really depends on the purpose.
I would guess that the NDAs in question are good for a year or more after the negotiations stop. Reason being they don't want 3M telling DuPont that we only asked $*** for the silk.
They actually could be (and should be)open ended after failure of talks so we will only hear when there is successful deal.
Good question....can vary tremendously...I signed an NDA in 2007, that I am still bound by...the final agreement was negotiated and signed, but I am still prevented from disclosing CERTAIN/SPECIFIC proprietary information.