Annotate any plot with reference lines and shaded bands. vline(x) and hline(y) mark axis values; vrect(x1, x2) and hrect(y1, y2) highlight valid ranges or target bands. Mix and match — they compose with every other plot primitive.

Want to make this yours?

Remix "Reference Lines on Graphs" into your own editable copy — tweak it, share it, make it yours.