NTS
3 letters
Historical clue formulations
- Some Windows systems — 2019-02-07
- Some Windows systems — 2015-05-15
- Some versions of Windows — 2014-03-30
- Some Windows systems — 2014-02-28
- Some Windows systems — 2012-09-14
- Some Windows systems — 2012-07-19
- Some Windows systems — 2011-06-05
- Some Windows systems — 2011-02-27
- Some Windows systems — 2010-12-30
- Windows options — 2010-02-05
- Some Windows systems — 2009-03-20
- Some Windows systems — 2004-07-18