Thanks for your quick response Franz 
However, square footage and precip rate are irrelevant to me as the type of zone I referred to is simply a single drip line watering water a row of trees, bushes, or shrubs with emitters. I already know my gallons per hour (or minute) usage and simply want to enter that information. This type of zone is very common and there should be an easy way to enter known GPH or GPM when square footage does not apply …
… I guess in the mean time I can use your calculation to come up with the number I need, but that is complicated and not user friendly. So, please let me know if this will work:
If I know that a zone is using 1 gallon per minute, then I would enter:
SF = 96.25
PR = 1
… and, according to you calculation, that should give me one gallon per minute?
Thanks again 