From the "Details" section of the current man page:
Paired X & Y values are plotted as scatterplot. The identity reference line (for Y=X) is drawn. Parallel projections of data points to (a lower-left) line segment show how each point relates to its X-Y = D difference; blue ‘crosses’ are used to display the distribution of difference scores and the mean difference is displayed as a heavy dashed (red) line_, parallel to the identity reference line. Means for X and Y are also plotted (as thin dashed vertical and horizontal lines), and rug plots are shown for the distributions of X (at the top of graphic) and Y (on the right side). *_Several summary statistics are plotted as well**, to facilitate both description and inference; see below. The 95% confidence interval for the population mean difference is also shown graphically. Because all data points are plotted relative to the identity line, and summary results are shown graphically, clusters, data trends, outliers, and possible uses of transformations are readily seen, possibly to be accommodated.
From the "Details" section of the current man page: