Historical clue formulations

• Prefix with structure — 2023-09-12
• Range of light that's invisible to the human eye — 2022-06-19
• Prefix with red or structure — 2021-03-22
• Red opening? — 2014-02-23
• Prefix with structure — 2013-04-02
• ___ dignitatem — 2011-05-22
• Prefix with sound — 2011-01-20
• Red leader? — 2009-11-29
• Prefix with red — 2009-10-07
• Prefix with structure — 2007-08-02
• Prefix with red — 2007-03-11
• Prefix with structure — 2006-12-05
• Prefix with red — 2006-11-22
• Red leader? — 2006-06-04
• Prefix with red — 2005-05-08
• Prefix with structure — 2003-07-29
• Prefix with structural — 2002-04-14
• Prefix with structure — 2000-11-26
• Prefix with red — 1999-05-17
• Prefix with red — 1999-05-09
• Prefix with structure — 1998-05-19
• Prefix with red — 1996-02-14