This article is from the Stardates in Star Trek FAQ, by Andrew Main zefram@dcs.warwick.ac.uk with numerous contributions by others.
SD 9521.5 corresponds to the date 2292-12-19. The digits run out and are
reset to zero on 2295-08-03. This starts a special `issue' of stardates,
whose sole purpose is to bridge the gap to 2323-01-01, when the new-style
stardates take over. In this new issue, SD 5000.0 is 2322-12-20, almost
exactly 30 years after STVI:TUC. This makes 2323-01-01 SD 5006.0. So
stardate 5006.0 in that issue became stardate 00000.0, and the date,
2323-01-01, became 2323*01*01 for the purposes of stardates.
If Thanksgiving were twelve days later, these numbers would be unbelievably
neat. So neat, in fact, that one might well reach the conclusion that this
system was actually designed to work this way.
 
Continue to: