To be precise...
The Jeppesen Flight star program is having different types of aircraft in its database.You pick the a/c,pick a route (ie orig-dest) and you get all you need regarding route,nav-log,filled ICAO plan,w&b...Now,default Flight Star IFR have bunch of a/c but no Jetstream.There is free online database of a/c on Jepp's web site but still no Jetstream in it.The program itself have a option of "build your own a/c model" but this requires slow and painful process of entering performance data.From this reason bunch of operators (or ops personal) post their a/c models on Jeppesen web for other to use them.
Hope that I was a bit more precise.Now, I am quite sure that Jetstream operators are using some kind of planning software and I would also like to know which one is it and pros and cons for it....
Best,
bgd