Normally,
PROC PLOT looks at the minimum difference between each pair of the five lowest
ordered values of each variable (the **delta**) and ensures that
there is no more than one of these intervals per print position on the final
scaled axis, if possible. If there is not enough room to do this, and if
PROC PLOT guesses that the data were artificially generated, it puts a fixed
number of deltas in each print position. Otherwise, it ignores the value.
Each
plot uses one full page unless the plot's size is changed by the VPOS= and
HPOS= options in the PLOT statement, the VPERCENT= or HPERCENT= options in
the PROC PLOT statement, or the PAGESIZE= and LINESIZE= system options. Titles,
legends, and variable labels are printed at the top of each page. Each axis
is labeled with the variable's name or, if it exists, the variable's label.
Normally, PROC PLOT begins a new plot on a new page. However, the VPERCENT=
and HPERCENT= options enable you to print more than one plot on a page. VPERCENT=
and HPERCENT= are described earlier in PROC PLOT Statement .

PROC PLOT always begins a new page after
a RUN statement and at the
beginning of a BY group.

If
values of either of the plotting variables are missing, PROC PLOT does not
include the observation in the plot. However, in a plot of Y*X, values of
X with corresponding missing values of Y are included in scaling the X axis,
unless the NOMISS option is specified in the PROC PLOT statement.
By default, PROC PLOT uses different plotting
symbols (A, B,
C, and so on) to represent observations whose values coincide on a plot. However,
if you specify your own plotting symbol or if you use the OVERLAY option,
you may not be able to recognize coinciding values.
If you specify a plotting symbol, PROC PLOT uses the same symbol regardless
of the number of observations whose values coincide. If you use the OVERLAY
option and overprinting is not in effect, PROC PLOT uses the symbol from the
first plot request. In both cases, the output includes a message telling you
how many observations are hidden.

Copyright 1999 by SAS Institute Inc., Cary, NC, USA. All rights reserved.