This article is from the Stardates in Star Trek FAQ, by Andrew Main zefram@dcs.warwick.ac.uk with numerous contributions by others.
Objection: this stardate system makes stardates round numbers of Terran days,
but the Klingons and Romulans and so on wouldn't use such a system.
We've never seen Romulans use a stardate. In fact, the only occasion when a
non-Federation person used a stardate was in the seventh season ST:TNG episode
"Liaisons". In that episode, an alien was trying to imitate a Federation
civilian. He had obtained logs from a crashed Federation ship, and had also
had some official contact with the Federation. So it seems clear that
stardates are a Federation invention, but their use is not limited to
Starfleet.
 
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