The Epilogue refers to the frames that have been provided at http://xkcd.com/1190/ since T** **d.
For the best explanation and the list of frames, see mscha's excellent page.
Musings, Theories and Wild Ass-guesses about the Epilogue
The pattern of frames after 2013-07-27T03:00+0:00 depends on a hash of the following numbers (in UTC zulu time):
- The one's place of the year
- The ten's place of the day
- The two-digit hour of day (00-23)
So to get the current frame letter, take the current date and truncate it leaving only the above information. Then look at the following table to determine the frame letter. (Frames 3090-3094 are labelled A-E)
|YDHH||Frame Letter Each Hour (00-23)|
|3000 to 3023||EDBADECBCBDCAECDBABABADC|
|3100 to 3123||CEABEABCBCDDEADEABABABCD|
|3300 to 3323||ABDEBCEADECACDABDECDCDAB|
|4000 to 4023||EDBADECBCBAECBDADCDCDBED|
|4100 to 4123||DEABEABCBCEABCABCDCDBCDE|
|4200 to 4223||DAEDCBAECDCBAEDCBADECDCB|
|4300 to 4323||ABDEBCEADEBCEACDABEADEBC|
|5000 to 5023||AECBDADCDCEDBADECBCBDCAE|
|5100 to 5123||EABCABCDCDCEABEABCBCDDEA|
|5200 to 5223||DBAEDCBADEBAEDCBAECDAEDC|
|5300 to 5323||BCEACDABEADBDEBCEADECACD|
Example: 2013-07-27T03:00+0:00 is truncated to 3203 which corresponds to BAEDCBAECDAEDCBAEDCCDCBA. 03 is the 4th hour of the day so the frame letter is 'D'.
Currently there are six exceptions to the above pattern.There seems to be some sloshing going on:
- In 2013, the first hour of the 10th day of every month is 'D'.
- In 2013, the first hour of the 30th day of every month is 'D'.
- In 2014, the first hour of the 10th day of every month is 'C'.
- In 2014, the first hour of the 20th day of every month is 'B'.
- In 2015, the first hour of the 10th day of every month is 'C'.
- In 2015, the first hour of the 20th day of every month is 'C'.
Example: 2013-12-10T00:00+0:00 should be 'C', but because of exception #1, it is 'D'.
The hash function is not known exactly. It may include other digits of the year and we won't know for sure until 2020 unless someone figures it out before then. The four patterns for each year are not random. In 2015, it was shown that it is possible to predict the entire year's sequence as soon as January 2nd (once the first day's pattern is known).