Historical clue formulations

• Like a plane, informally — 2026-02-26
• Flat, for short — 2023-02-16
• Flat, for short — 2022-10-19
• Lacking depth, informally — 2018-11-19
• Having no depth, briefly — 2013-12-24
• Like most movies — 2013-06-13
• Like traditional movies, for short — 2012-06-19
• Lacking depth, in brief — 2012-03-04
• Like flicks seen without special glasses — 2011-08-09
• Having length and width only, briefly — 2010-01-25
• Lacking depth — 2009-02-26
• Flat — 2009-01-16
• Lacking depth — 2006-04-20
• Having no depth — 2001-11-28
• Lacking depth — 2001-05-30
• Flat — 1999-04-25