You don't understand the startdates?
Take, for example, 19981217.1521
Let me stick some spaces in some helpful places:
1998 12 17 . 15 21
That better?
19981217 means 17th December 1998, and 1521 is in 24-hour clock format, IE 3:21PM
Stardates in the Star Trek universe work in an entirely different way. Wikipedia has a good explanation on how Stardates work.