Historical clue formulations

• Face-saving aid at a reunion — 2019-06-28
• Guard / It might say "Hello" — 2019-04-09
• Sticker that might start "Hello ..." — 2018-06-11
• Written introduction? — 2015-09-29
• Retail clerk's accessory — 2014-11-23
• Part of many a welcome kit — 2013-01-04
• It may be worn around the neck at a convention — 2009-11-23
• Conventioneer's wear — 2008-02-26
• "Hello" sticker — 2008-01-08
• Convention pin-on — 2006-12-12
• Means of introduction — 2006-03-03
• Luggage attachment — 2005-03-15
• Convention handout — 2002-07-06
• It may say "Hello" — 2000-01-16