Historical clue formulations

• Made certain — 2024-05-14
• Guaranteed — 2021-11-16
• Made certain — 2019-05-13
• Double-checked, e.g. — 2014-04-13
• Made safe — 2009-05-14
• Sealed — 2008-04-12
• Guaranteed — 2003-08-07
• Guaranteed — 2002-01-09
• Guarded — 2001-12-08
• Left no doubt about — 1999-05-06
• Safeguarded — 1998-05-20