That image is slightly deceiving... There is no ABSOLUTE length unit known as a Reaper grid, since the grid can be adjusted. So, that image can be used as a guide IF your grid corresponds to 4 beats per measure (I'm not in front of Reaper but I think this is represented as "1/4").
So, what that image is telling you is that if your Reaper grid is set to 4 grid divisions per measure, and you draw a note that starts on a grid line, intersects 3 grid lines, and ends on a grid line (ie. is 4 beats long), then you will have drawn a "whole note".
|