System_Name,Effective_Date,Notes
NAICS 2022,2022-01-01,Current active standard (as of 2022).
NAICS 2017,2017-01-01,Replaced by 2022 revision.
NAICS 2012,2012-01-01,Replaced by 2017 revision.
SIC 1987,1987-01-01,Replaced by NAICS in 1997 but widely used for historical continuity.