The coordinates can be passed in a plotting structure
(a list with x and y components), a two-column matrix, a
time series, …. See xy.coords. If supplied
separately, they must be of the same length.
The coordinates can contain NA values. If a point contains
NA in either its x or y value, it is omitted from
the plot, and lines are not drawn to or from such points. Thus
missing values can be used to achieve breaks in lines.
For type = "h", col can be a vector and will be recycled
as needed.
lwd can be a vector: its first element will apply to lines but
the whole vector to symbols (recycled as necessary).