You don't understand the startdates?
Take, for example, 19981207.1200
Let me stick some spaces in some helpful places:
1998 12 07 . 12 00
That better?
19981207 means 7th December 1998, and 1200 is in 24-hour clock format, IE 12:00 midday
Stardates in the Star Trek universe work in an entirely different way. Wikipedia has a good explanation on how Stardates work.