A point in one dimension, as in a dot plot.
scaleX is in scope, the dot will be positioned out from the left of the chart.
scaleY is in scope, the dot will be positioned up from the bottom of the chart.
scaleY must be in scope, but not both.
The dimension of the data which should be used to position the dot.
Relative position can be interpreted very accurately by the human perceptual system, making dots (and their two-dimensional analog, points) an excellent choice for representing any quantitative measure.
Compared to bars, dots use much less ink. Unlike bars, dots can be used effectively with scales that do not start at 0.