Raildriver & Throttle Percentages

I note that throttle advancement vary from loco to loco. On a first key press of letter "A", some jump to 7%, some to 13%. I suspect this is what the author(s) have built into each model. Just wondering if using Raildriver allows a progressive advancement of the throttle starting at 0%, 1%, 2%, 3% and so forth upward or would the first notch of throttle engagement be what the author has coded into the model?