Just a very quick blog post!

I had exactly the same problem in a piece of code yesterday that Sony had with their PS3 and the PSN yesterday. It’s looks like its because Sony (and I) were using the ISO year.

The article which helped me with my code is here:

http://stackoverflow.com/questions/1978051/zend-datetostring-outputs-the-wrong-year-bug-in-my-code-or-zend-date

And the Wikipedia page that explains it here too:

http://en.wikipedia.org/wiki/ISO_week_date

“The system has a 400-year cycle of 146 097 days (20 871 weeks), with an average year length of exactly 365.2425 days, just like the Gregorian calendar. In every 400 years there are 71 years with 53 weeks.”