(Rotary Tool Center Point)
I bookmarked this article a few years back. It explains fairly well. Article is for (G43.5 vector programming), instead of the (G43.4 rotary value programming), but still gives a good explanation of (Rotary Tool Center Point).
You are basically programming relative to the part, the machine will calculate the proper feedrates, regardless of where the part is on the table.
Imagine you had two identical programs, part and machines, but one setup had a distance further from center of rotation. The setup that is further from "center of rotation" would require the linear axes to move further due to the larger swing, and would have an actual different (faster) feedrate. The speed of tool relative to parts would still be identical on both setups though.
In principle the Inverse Time feedrate can also be used when not using RTCP. It simply tells how long the controller should take to move to the end position of that line, regardles of the mode you are in.
This is higly dependent on the controller you are using.
Correct, the post outputs Degrees/Min (DPM) on a rotary only move. Fortunately DPM is still the same no matter how far you are from center of rotation. It's the linears that end up having to do the feedrate compensating.