G'day Brett and sorry for the topic hijack, it went in a direction I didn't expect.
As I've been told, " Short Circuit " came about because there was a lack of suitable road racing tracks back in the day which is why the early tracks were quite long compared with todays tracks.
DT is our modern day name and Flattrack is basically the US equivelant.
So in answere to your question, in Australia, DT, Flattrack & Short Circuit all fall under the same explanation.
Then there's, Longtrack, Shorttrack & even Track racing.
If you're confused then so am I sometimes.