http://rorate-caeli.blogspot.com/2010/12/december-2324-just-reminder-that.htmlAccording to the chapter on "Feasts and Fasts throughout the Year" in The New Marian Missal for Daily Mass, compiled by Fr. Sylvester P. Juergens SM and published by Regina Press, NY, in 1963, December 24 was a day of fasting and complete abstinence in the United Kingdom, Ireland and the USA. In Canada and the Philippines the fasting and abstinence of December 24 were moved to December 23.
http://paramedicgoldengirl.blogspot.com/2008/02/pre-vatican-ii-fasting-guidelines.htmlComplete abstinence is to be observed on all Fridays of the year, Ash Wednesday, Vigils of the Immaculate Conception and Christmas, and on Holy Saturday. Partial abstinence is to be observed on Ember Wednesdays and Saturdays, and on the Vigil of Pentecost.
http://www.sspxasia.com/Docuмents/The_Church_Year/first-Sunday-of-advent.htm
Which are the most important fast days, and days of abstinence?
All the weekdays of Lent; the Fridays in Advent; the Ember days for the four seasons of the year; and the Vigils of All-Saints, Christmas, Whitsunday, and the Assumption. If the Feast, however, occurs on Monday, the vigil is kept on the Saturday before; as Sunday is never a fast day.'