On Jan 11, 1999 [1-99]
President Clinton issued exec order 13110 to form a working group to locate, inventory, and recommend for declassification, all classified Nazi criminal war records.
In this anon's opinion what to declass also means what to stay classified. I think there's something here.
Classified Jan 1999 [class 1-99]
https://fas.org/sgp/clinton/eo13110.html