Stardates Explained - 19990216.1012

You don't understand the startdates?

Take, for example, 19990216.1012

Let me stick some spaces in some helpful places:

1999 02 16 . 10 12

That better?

19990216 means 16th February 1999, and 1012 is in 24-hour clock format, IE 10:12AM

Stardates in the Star Trek universe work in an entirely different way. Wikipedia has a good explanation on how Stardates work.