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 for this interval arrangement, and if PROC PLOT guesses that the data was artificially generated, then it puts a fixed number of deltas in each print position. Otherwise, PROC PLOT 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.

The PLOT procedure assigns a name to each table that it creates. You can use these names to reference the table when using the Output Delivery System (ODS) to select tables and create output data sets. For more information, see ODS Table Names and the Base SAS Procedures That Produce Them in SAS Output Delivery System: User's Guide.

Under certain circumstances, using PROC PLOT with the Output Delivery System produces files that are not portable. If the SAS system option FORMCHAR= in your SAS session uses nonstandard line-drawing characters, then the output might include strange characters instead of lines in operating environments in which the SAS Monospace font is not installed. To avoid this problem, specify the following OPTIONS statement before executing PROC PLOT:

options formchar="|----|+|---+=|-/\<>*";

If values of either of the plotting variables are missing, then 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, then you might not be able to recognize coinciding values.

If you specify a plotting symbol, then 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, then 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.