It's been about 16 years, but I was forced to teach myself how to use the FAPT programming software on a Hitachi-Sieki lathe when our lathe guy had a heart attack. We were making gear blanks for the new Airforce One at the time.
From what I remember, you first had to draw the shape of the part using the number keys on the key pad. The number keys had the symbals for lines and arcs along with the numbers. It seems the control did have the ability to trig. end points if you didn't have all of the numbers needed. After the shape was drawn, you choose from a library of tools, which tool to rough with and define the area by using little markers on your graphics to define the zone to generate tool path. The control also had enough smarts to determine whether or not a particular tool could go into grooves or not. After roughing you could choose the next tool define the area to cut and continue on.
When finished, it would generate code for you. Seems like we had do some editing afterwards.
It has been long time since using the FAPT programming, but I think it worked along those lines anyhow.It was pretty easy to use and could generate a pretty long program fast.
I would use again if I had to.