Historical clue formulations

• Basic plot lines? — 2024-09-10
• Bottom lines? — 2020-11-01
• Horizontal lines on graphs — 2015-11-03
• Baselines? — 2013-11-16
• Base lines — 2004-05-30
• Graph lines — 1994-11-20
• Bottoms of graphs — 1994-08-01