-
-To produce output in PDF, PostScript, and SVG formats, specify
-@option{-o @var{file}} on the @pspp{} command line, optionally followed
-by any of the options shown in the table below to customize the output
-format.
-
-PDF, PostScript, and SVG output is only available if your installation
-of @pspp{} was compiled with the Cairo library.
+@cindex PNG
+
+To produce output in PDF, PostScript, SVG, or PNG format, specify
+@option{-o @var{file}} on the @pspp{} command line, optionally
+followed by any of the options shown in the table below to customize
+the output format.
+
+PDF, PostScript, and SVG use real units: each dimension among the
+options listed below may have a suffix @samp{mm} for millimeters,
+@samp{in} for inches, or @samp{pt} for points. Lacking a suffix,
+numbers below 50 are assumed to be in inches and those about 50 are
+assumed to be in millimeters.
+
+PNG files are pixel-based, so dimensions in PNG output must ultimately
+be measured in pixels. For output to these files, PSPP translates the
+specified dimensions to pixels at 72 pixels per inch. For PNG output
+only, fonts are by default rendered larger than this, at 96 pixels per
+inch.
+
+An SVG or PNG file can only hold a single page. When PSPP outputs
+more than one page to SVG or PNG, it creates multiple files. It
+outputs the second page to a file named with a @code{-2} suffix, the
+third with a @code{-3} suffix, and so on.