Historical clue formulations

• When repeated, Mork's farewell — 2020-05-27
• When repeated, an old sitcom catchphrase — 2017-06-04
• When repeated, Mork's sign-off — 2017-02-09
• When doubled, a sitcom sign-off — 2016-07-19
• When repeated, Mork's sign-off — 2014-12-23
• When doubled, part of many a Robin Williams tribute — 2014-12-14
• Half of Mork's farewell — 2014-10-12
• Part of a sitcom sign-off — 2012-12-20
• When repeated, a TV sign-off — 2011-07-24
• Half of a sitcom farewell — 2011-06-12
• When repeated, Mork's sign-off — 2011-05-25
• When repeated, a classic sitcom sign-off — 2011-03-21
• Half of Mork's sign-off — 2010-12-07
• TV alien's word — 2010-02-28
• Half of Mork's goodbye — 2009-01-05
• Half of Mork's sitcom sign-off — 2008-09-02
• When doubled, an old sitcom sign-off — 2008-08-31
• When repeated, Mork's TV sign-off — 2008-06-15
• When doubled, a Robin Williams character's catchphrase — 2007-10-28
• When doubled, an old sitcom goodbye — 2007-08-14
• When doubled, an old sitcom goodbye — 2006-08-02
• When repeated, an old TV sign-off — 2006-07-30
• When repeated, Mork's TV sign-off — 2005-08-07
• Half of a TV alien's send-off — 2004-05-30
• Half an Orkan farewell — 2004-01-13
• Half of Mork's greeting — 2003-04-27
• When doubled, a sitcom sign-off — 2001-11-09
• Half of Mork's sign-off — 2001-08-02
• Half of Mork's sign-off — 2001-03-25
• Part of a sitcom sign-off — 2000-12-30
• Half of Mork's sign-off — 2000-04-19
• Half of Mork's sign-off — 2000-01-05
• When doubled, an old TV signoff — 1999-07-09
• Part of Mork's goodbye — 1996-11-28
• Half of Mork's greeting — 1995-04-06
• Half of Mork's sign-off — 1994-07-13
• Part of Mork's sign-off — 1993-12-11