Historical clue formulations

• Christmas or Thanksgiving: Abbr. — 2009-05-11
• Dec. 25, e.g. — 2008-04-17
• Christmas, e.g.: Abbr. — 2003-10-25
• July 4, e.g.: Abbr. — 2000-06-04
• ___ Hamoed (Passover period) — 1999-07-02