Historical clue formulations

• Kind of marker — 2016-12-04
• Marker's mark maker — 2014-01-31
• Sharpie feature — 2013-07-03
• Kind of marker — 2010-05-14
• Kind of pen — 2009-01-24
• Feature of a certain pen — 2004-09-26
• Marker's marker — 2000-11-26