Two keywords control whether or not every point in the plot is marked with a symbol, **pointinterval** (short form **pi**) and **pointnumber** (short form **pn**).

**pi N** or **pi -N** tells gnuplot to only place a symbol on every Nth point. A negative value for N will erase the portion of line segment that passes underneath the symbol. The size of the erased portion is controlled by **set pointintervalbox**.

**pn N** or **pn -N** tells gnuplot to label only N of the data points, evenly spaced over the data set. As with **pi**, a negative value for N will erase the portion of line segment that passes underneath the symbol.

Copyright 1986 - 1993, 1998, 2004 Thomas Williams, Colin Kelley

Distributed under the gnuplot license (rights to distribute modified versions are withheld).