A guy from 1997 has the exact same question I do now... hopefully
someone can answer it (because he had no responses back then!)... I
am
gonna repost his question:

I am trying to plot a chart containing data similar to that shown
below, without much success:


Sprinkler OnTime OffTime
Front 0815 0845
Front 1445 1600
Front 1700 1730
Back 0900 0930
Back 1800 1830
Left 1100 1115
Right 1130 1215
Right 1900 1930
Right 2000 2030


I'd like to see a graph with four (discontinuous) horizontal lines,
each line corresponding to one of the sprinklers. The X axis is
plotted
from 0000 to 2400, and each line is visible when the sprinkler is on.