Here is a Traffic Tools (TTools) Flight Plan from San Diego International airport (KSAN) to Avalon Island (KAVX) in a Junkers slow and low mini liner.
Here is the flightplan string;
AC#880,N29696,1%,24Hr,VFR,17:00:21,17:49:20,080,R,0000,KAVX,20:46:16,21:35:15,080,R,0000,KSAN
Note that the first part of the string shows the aircraft, call sign
AC#880,N29696,
Second shows its AI traffic setting 'least amount', then how often it resumes, (this one restarts once every 24 hours).. You can have every hour, every two hours, six, eight, 24, and weekly) This one is also a VFR flight.
1%,24Hr,VFR,
If this was a weekly flight, you would include the day of the week, 1 thru 7, with 1 being Sunday. This is not a weekly flight, so the day of the week is not at the end past VFR (or if you like, IFR).
Third is the 'first leg flight', or 'where you are going to' starts at 17:00 GMT and flies at an altitude of 8,000 feet (080)
17:00:21,17:49:20,080,R,0000,KAVX
The Second or in this case, the final leg, must return to the original location. (All AI flights must return home, so the last flight leg is actually the beginning location). This one takes off at 20:46 GMT, lands at 21:35 GMT roughly, flies at 8,000 feet (FL is 080), and destination/home is KSAN or San Diego International.
20:46:16,21:35:15,080,R,0000,KSAN
Now you can read a FP string and easily switch out the plane, times, airports, etc. You could also copy/paste this line, change the N number, and reverse the airfields (since they are both in teh same time zone) and Voila, you have a second flight plan, reversed. (All planes could have the same N Number, but sounds goofy over the ATC).
:d
Easy peasy....
There are also some other tidbits you can add, like military call sign use for ATC, good with IFR flights. You can also assign them to do touch and goes by adding say 30 min's to a FP (with smaller planes) and then add TNG in front of the 'arrival' time at that airfield you wish your plane to do touch and goes. This isnt good for big jets as they have a huge traffic pattern. One lap can take 30 min's at least and usually cause your bird not to arrive (disappear) and also tie up traffic.
Bill