Friday in the Octave of Christmas

Last Christmas, there arose a question in my family as to whether the Friday in the Octave of Christmas is a day of penance. Apparently the question arises elsewhere also, and, as Fr. Zuhlsdorf demonstrated, the answer is not self-evident. My research last year, which I present here for the sake of reference, indicated that Friday in the Octave of Christmas is not a solemnity, and thus is a day of penance. To wit:

1. Christmas does have an Octave in the Ordinary Form calendar. See Gen. Norms for the Liturgical Year & the Calendar ¶ 35. 
2. The days in the Octave of Christmas, however, do not appear to be Solemnities. Compare id. with id. ¶ 24 (specifying that days within the Octave of Easter are Solemnities). 
3. For this reason, the Friday in the Octave of Christmas is a day of abstinence or the alternative penance stipulated by the episcopal conference, pursuant to Canon 1251, which excepts only solemnities.
4.  The traditional practice, which derived from the 1917 Code of Canon Law and not from the Missale Romanum or its affiliated liturgical norms (and thus is not resurrected by Summorum pontificum or Universae Ecclesiae), abrogated the obligation of abstinence on the basis of whether or not a Friday was a "day of precept," that is, of obligation. Since under the Extraordinary Form calendar and the 1917 Code of Canon Law the Friday in the Octave of Christmas is not a day of obligation, the traditional observance would make the Friday in the Octave of Christmas a day of abstinence. See 1917 CIC c. 1252 § 4. That day is not a day of obligation under the modern calendar either universally or in the United States, either. See Liturgical Calendar for the Dioceses of the United States of America 2011 at 42. Reference to the Extraordinary Form calendar shows that the Friday in the Octave of Christmas is, in fact, only a second-class feast, suggesting that the distinction between paragraphs 24 and 35 of the modern General Norms is not a scrivener's error. 
5. That is, Friday in the Octave was not a day of precept or a solemnity in 2011 in the United States. At the same time, none of the universal days of obligation established by the 1983 CIC fall during the Octave. I can't imagine how a day in the Octave could become one of obligation, but your local solemnity mileage may vary depending on what day of the week Christmas is. (Isn't, for instance, the feast of St. Thomas a Becket a solemnity in England or parts thereof?)
6. Thus, assuming that the English version of the General Norms is an accurate translation, Canon Law binds all persons to observe the Friday in the Octave of Christmas, as a day of penance (assuming that one does not live in a place where the day is made a solemnity by virtue of a local patronal feast, see #5). If one habitually practices that penance by abstaining from meat, one should abstain on that day. If one is accustomed to abstain pursuant to the norms associated with the usus antiquior, one should abstain.
7. I appear to have located the General Norms, as well as Paul VI's motu propio promulgating them (Approval of the General Norms for the Liturgical Year and the New General Roman Calendar) from the ICEL website.