On 7 December, the U.S. Bureau of Labor Statistics (BLS) announced (citation, USDL-18-1912):

Revision of Seasonally Adjusted Household Survey Data

In accordance with usual practice, The Employment Situation news release for December 2018, scheduled for January 4, 2019, will incorporate annual revisions in seasonally adjusted household survey data. Seasonally adjusted data for the most recent 5 years are subject to revision. 

The BLS conducts two complementary monthly employment surveys, the Current Population Survey (CPS, household employment) and the Current Employment Statistics (CES, payroll employment, establishment survey). Subsequent articles in Data Buffet News will enumerate the impacts; as always, they will be cross-referenced through Mnemonic 411.