[pspp-builds.git] / doc / configuring.texi

@node Configuration, Portable File Format, Installation, Top
@appendix Configuring PSPP
@cindex configuration
@cindex PSPP, configuring

PSPP has dozens of configuration possibilities and hundreds of
settings.  This is both a bane and a blessing.  On one hand, it's
possible to easily accommodate diverse ranges of setups.  But, on the
other, the multitude of possibilities can overwhelm the casual user.
Fortunately, the configuration mechanisms are profusely described in the
sections below@enddots{}

@menu
* File locations::              How PSPP finds config files.
* Configuration techniques::    Many different methods of configuration@enddots{}
* Configuration files::         How configuration files are read.
* Environment variables::       All about environment variables.
* Output devices::              Describing your terminal(s) and printer(s).
* PostScript driver class::     Configuration of PostScript devices.
* ASCII driver class::          Configuration of character-code devices.
* HTML driver class::           Configuration for HTML output.
* Miscellaneous configuring::   Even more configuration variables.
* Improving output quality::    Hints for producing ever-more-lovely output.
@end menu

@node File locations, Configuration techniques, Configuration, Configuration
@section Locating configuration files

PSPP uses the same method to find most of its configuration files:

@enumerate
@item
The @dfn{base name} of the file being sought is determined.

@item
The path to search is determined.  

@item
Each directory in the search path, from left to right, is searched for a
file with the name of the base name.  The first occurrence is read
as the configuration file.
@end enumerate

The first two steps are elaborated below for the sake of our pedantic
friends.

@enumerate
@item
A @dfn{base name} is a file name lacking an absolute directory
reference.  Some examples of base names are: @file{ps-encodings},
@file{devices}, @file{devps/DESC} (under UNIX), @file{devps\DESC} (under
M$ environments).

Determining the base name is a two-step process:

@enumerate a
@item
If the appropriate environment variable is defined, the value of that
variable is used (@pxref{Environment variables}).  For instance, when
searching for the output driver initialization file, the variable
examined is @code{STAT_OUTPUT_INIT_FILE}.

@item
Otherwise, the compiled-in default is used.  For example, when searching
for the output driver initialization file, the default base name is
@file{devices}.
@end enumerate

@strong{Please note:} If a user-specified base name does contain an
absolute directory reference, as in a file name like
@file{/home/pfaff/fonts/TR}, no path is searched---the file name is used
exactly as given---and the algorithm terminates.

@item
The path is the first of the following that is defined:

@itemize @bullet
@item
A variable definition for the path given in the user environment.  This
is a PSPP-specific environment variable name; for instance,
@code{STAT_OUTPUT_INIT_PATH}.

@item 
In some cases, another, less-specific environment variable is checked.
For instance, when searching for font files, the PostScript driver first
checks for a variable with name @code{STAT_GROFF_FONT_PATH}, then for
one with name @code{GROFF_FONT_PATH}.  (However, font searching has its
own list of esoteric search rules.)

@item
The configuration file path, which is itself determined by the
following rules:

@enumerate a
@item
If the command line contains an option of the form @samp{-B @var{path}}
or @samp{--config-dir=@var{path}}, then the value given on the
rightmost occurrence of such an option is used.

@item
Otherwise, if the environment variable @code{STAT_CONFIG_PATH} is
defined, the value of that variable is used.

@item
Otherwise, the compiled-in fallback default is used.  On UNIX machines,
the default fallback path is

@enumerate 1
@item
@file{~/.pspp}

@item
@file{/usr/local/lib/pspp}

@item
@file{/usr/lib/pspp}
@end enumerate

On DOS machines, the default fallback path is:

@enumerate 1
@item
All the paths from the DOS search path in the @samp{PATH} environment
variable, in left-to-right order.

@item
@file{C:\PSPP}, as a last resort.
@end enumerate

Note that the installer of PSPP can easily change this default
fallback path; thus the above should not be taken as gospel.
@end enumerate
@end itemize
@end enumerate

As a final note: Under DOS, directories given in paths are delimited by
semicolons (@samp{;}); under UNIX, directories are delimited by colons
(@samp{:}).  This corresponds with the standard path delimiter under
these OSes.

@node Configuration techniques, Configuration files, File locations, Configuration
@section Configuration techniques

There are many ways that PSPP can be configured.  These are
described in the list below.  Values given by earlier items take
precedence over those given by later items.

@enumerate
@item
Syntax commands that modify settings, such as @cmd{SET}.  @xref{SET}.

@item
Command-line options.  @xref{Invocation}.

@item
PSPP-specific environment variable contents.  @xref{Environment
variables}.

@item
General environment variable contents.  @xref{Environment variables}.

@item
Configuration file contents.  @xref{Configuration files}.

@item
Fallback defaults.
@end enumerate

Some of the above may not apply to a particular setting.

@node Configuration files, Environment variables, Configuration techniques, Configuration
@section Configuration files

Most configuration files have a common form:

@itemize @bullet
@item
Each line forms a separate command or directive.  This means that lines
cannot be broken up, unless they are spliced together with a trailing
backslash, as described below.

@item
Before anything else is done, trailing white space is removed.

@item
When a line ends in a backslash (@samp{\}), the backslash is removed,
and the next line is read and appended to the current line.

@itemize @minus
@item
White space preceding the backslash is retained.

@item
This rule continues to be applied until the line read does not end in a
backslash.

@item
It is an error if the last line in the file ends in a backslash.
@end itemize

@item
Comments are introduced by an octothorpe (@samp{#}), and continue until the
end of the line.

@itemize @minus
@item
An octothorpe inside balanced pairs of double quotation marks (@samp{"})
or single quotation marks (@samp{'}) does not introduce a comment.

@item
The backslash character can be used inside balanced quotes of either
type to escape the following character as a literal character.  

(This is distinct from the use of a backslash as a line-splicing
character.)

@item
Line splicing takes place before comment removal.
@end itemize

@item
Blank lines, and lines that contain only white space, are ignored.
@end itemize

@node Environment variables, Output devices, Configuration files, Configuration
@section Environment variables

You may think the concept of environment variables is a fairly simple
one.  However, the author of PSPP has found a way to complicate
even something so simple.  Environment variables are further described
in the sections below:

@menu
* Variable values::             Values of variables are determined this way.
* Environment substitutions::   How environment substitutions are made.
* Predefined variables::        A few variables are automatically defined.
@end menu

@node Variable values, Environment substitutions, Environment variables, Environment variables
@subsection Values of environment variables

Values for environment variables are obtained by the following means,
which are arranged in order of decreasing precedence:

@enumerate
@item
Command-line options.  @xref{Invocation}.

@item
The @file{environment} configuration file---more on this below.

@item
Actual environment variables (defined in the shell or other parent
process).
@end enumerate

The @file{environment} configuration file is located through application
of the usual algorithm for configuration files (@pxref{File locations}),
except that its contents do not affect the search path used to find
@file{environment} itself.  Use of @file{environment} is discouraged on
systems that allow an arbitrarily large environment; it is supported for
use on systems like MS-DOS that limit environment size.

@file{environment} is composed of lines having the form
@samp{@var{key}=@var{value}}, where @var{key} and the equals sign
(@samp{=}) are required, and @var{value} is optional.  If @var{value} is
given, variable @var{key} is given that value; if @var{value} is absent,
variable @var{key} is undefined (deleted).  Variables may not be defined
with a null value.

Environment substitutions are performed on each line in the file
(@pxref{Environment substitutions}).

See @ref{Configuration files}, for more details on formatting of the
environment configuration file.

@quotation
@strong{Please note:} Support for @file{environment} is not yet
implemented.
@end quotation

@node Environment substitutions, Predefined variables, Variable values, Environment variables
@subsection Environment substitutions

Much of the power of environment variables lies in the way that they may
be substituted into configuration files.  Variable substitutions are
described below.

The line is scanned from left to right.  In this scan, all characters
other than dollar signs (@samp{$}) are retained unmolested.  Dollar
signs, however, introduce an environment variable reference.  References
take three forms:

@table @code
@item $@var{var}
Replaced by the value of environment variable @var{var}, determined as
specified in @ref{Variable values}.  @var{var} must be one of the
following:

@itemize @bullet
@item
One or more letters.

@item
Exactly one nonalphabetic character.  This may not be a left brace
(@samp{@{}).
@end itemize

@item $@{@var{var}@}
Same as above, but @var{var} may contain any character (except
@samp{@}}).

@item $$
Replaced by a single dollar sign.
@end table

Undefined variables expand to a empty value.

@node Predefined variables,  , Environment substitutions, Environment variables
@subsection Predefined environment variables

There are two environment variables predefined for use in environment
substitutions:

@table @samp
@item VER
Defined as the version number of PSPP, as a string, in a format
something like @samp{0.9.4}.

@item ARCH
Defined as the host architecture of PSPP, as a string, in standard
cpu-manufacturer-OS format.  For instance, Debian GNU/Linux 1.1 on an
Intel machine defines this as @samp{i586-unknown-linux}.  This is
somewhat dependent on the system used to compile PSPP.
@end table

Nothing prevents these values from being overridden, although it's a
good idea not to do so.

@node Output devices, PostScript driver class, Environment variables, Configuration
@section Output devices

Configuring output devices is the most complicated aspect of configuring
PSPP.  The output device configuration file is named
@file{devices}.  It is searched for using the usual algorithm for
finding configuration files (@pxref{File locations}).  Each line in the
file is read in the usual manner for configuration files
(@pxref{Configuration files}).

Lines in @file{devices} are divided into three categories, described
briefly in the table below:

@table @i
@item driver category definitions
Define a driver in terms of other drivers.

@item macro definitions
Define environment variables local to the the output driver
configuration file.

@item device definitions
Describe the configuration of an output device.
@end table

The following sections further elaborate the contents of the
@file{devices} file.

@menu
* Driver categories::           How to organize the driver namespace.
* Macro definitions::           Environment variables local to @file{devices}.
* Device definitions::          Output device descriptions.
* Dimensions::                  Lengths, widths, sizes, @enddots{}
* papersize::                   Letter, legal, A4, envelope, @enddots{}
* Distinguishing line types::   Details on @file{devices} parsing.
* Tokenizing lines::            Dividing @file{devices} lines into tokens.
@end menu

@node Driver categories, Macro definitions, Output devices, Output devices
@subsection Driver categories

Drivers can be divided into categories.  Drivers are specified by their
names, or by the names of the categories that they are contained in.
Only certain drivers are enabled each time PSPP is run; by
default, these are the drivers in the category `default'.  To enable a
different set of drivers, use the @samp{-o @var{device}} command-line
option (@pxref{Invocation}).

Categories are specified with a line of the form
@samp{@var{category}=@var{driver1} @var{driver2} @var{driver3} @var{@dots{}}
@var{driver@var{n}}}.  This line specifies that the category
@var{category} is composed of drivers named @var{driver1},
@var{driver2}, and so on.  There may be any number of drivers in the
category, from zero on up.

Categories may also be specified on the command line
(@pxref{Invocation}).

This is all you need to know about categories.  If you're still curious,
read on.

First of all, the term `categories' is a bit of a misnomer.  In fact,
the internal representation is nothing like the hierarchy that the term
seems to imply: a linear list is used to keep track of the enabled
drivers.

When PSPP first begins reading @file{devices}, this list contains
the name of any drivers or categories specified on the command line, or
the single item `default' if none were specified.

Each time a category definition is specified, the list is searched for
an item with the value of @var{category}.  If a matching item is found,
it is deleted.  If there was a match, the list of drivers (@var{driver1}
through @var{driver@var{n}}) is then appended to the list.

Each time a driver definition line is encountered, the list is searched.
If the list contains an item with that driver's name, the driver is
enabled and the item is deleted from the list.  Otherwise, the driver
is not enabled.

It is an error if the list is not empty when the end of @file{devices}
is reached.

@node Macro definitions, Device definitions, Driver categories, Output devices
@subsection Macro definitions

Macro definitions take the form @samp{define @var{macroname}
@var{definition}}.  In such a macro definition, the environment variable
@var{macroname} is defined to expand to the value @var{definition}.
Before the definition is made, however, any macros used in
@var{definition} are expanded.

Please note the following nuances of macro usage:

@itemize @bullet
@item
For the purposes of this section, @dfn{macro} and @dfn{environment
variable} are synonyms.

@item
Macros may not take arguments.

@item
Macros may not recurse.

@item
Macros are just environment variable definitions like other environment
variable definitions, with the exception that they are limited in scope
to the @file{devices} configuration file.

@item
Macros override other all environment variables of the same name (within
the scope of @file{devices}).

@item
Earlier macro definitions for a particular @var{key} override later
ones.  In particular, macro definitions on the command line override
those in the device definition file.  @xref{Non-option Arguments}.

@item
There are two predefined macros, whose values are determined at runtime:

@table @samp
@item viewwidth
Defined as the width of the console screen, in columns of text.

@item viewlength
Defined as the length of the console screen, in lines of text.
@end table
@end itemize

@node Device definitions, Dimensions, Macro definitions, Output devices
@subsection Driver definitions

Driver definitions are the ultimate purpose of the @file{devices}
configuration file.  These are where the real action is.  Driver
definitions tell PSPP where it should send its output.

Each driver definition line is divided into four fields.  These fields
are delimited by colons (@samp{:}).  Each line is subjected to
environment variable interpolation before it is processed further
(@pxref{Environment substitutions}).  From left to right, the four
fields are, in brief:

@table @i
@item driver name
A unique identifier, used to determine whether to enable the driver.

@item class name
One of the predefined driver classes supported by PSPP.  The
currently supported driver classes include `postscript' and `ascii'.

@item device type(s)
Zero or more of the following keywords, delimited by spaces:

@table @code
@item screen

Indicates that the device is a screen display.  This may reduce the
amount of buffering done by the driver, to make interactive use more
convenient.

@item printer

Indicates that the device is a printer.

@item listing

Indicates that the device is a listing file.
@end table

These options are just hints to PSPP and do not cause the output to be
directed to the screen, or to the printer, or to a listing file---those
must be set elsewhere in the options.  They are used primarily to decide
which devices should be enabled at any given time.  @xref{SET}, for more
information.

@item options
An optional set of options to pass to the driver itself.  The exact
format for the options varies among drivers.
@end table

The driver is enabled if:

@enumerate
@item
Its driver name is specified on the command line, or

@item
It's in a category specified on the command line, or

@item
If no categories or driver names are specified on the command line, it
is in category @code{default}.
@end enumerate

For more information on driver names, see @ref{Driver categories}.

The class name must be one of those supported by PSPP.  The
classes supported depend on the options with which PSPP was
compiled.  See later sections in this chapter for descriptions of the
available driver classes.

Options are dependent on the driver.  See the driver descriptions for
details.

@node Dimensions, papersize, Device definitions, Output devices
@subsection Dimensions

Quite often in configuration it is necessary to specify a length or a
size.  PSPP uses a common syntax for all such, calling them
collectively by the name @dfn{dimensions}.

@itemize @bullet
@item
You can specify dimensions in decimal form (@samp{12.5}) or as
fractions, either as mixed numbers (@samp{12-1/2}) or raw fractions
(@samp{25/2}).

@item 
A number of different units are available.  These are suffixed to the
numeric part of the dimension.  There must be no spaces between the
number and the unit.  The available units are identical to those offered
by the popular typesetting system @TeX{}:

@table @code
@item in
inch (1 @code{in} = 2.54 @code{cm})

@item "
inch (1 @code{in} = 2.54 @code{cm})

@item pt
printer's point (1 @code{in} = 72.27 @code{pt})

@item pc
pica (12 @code{pt} = 1 @code{pc})

@item bp
PostScript point (1 @code{in} = 72 @code{bp})

@item cm
centimeter

@item mm
millimeter (10 @code{mm} = 1 @code{cm})

@item dd
didot point (1157 @code{dd} = 1238 @code{pt})

@item cc
cicero (1 @code{cc} = 12 @code{dd})

@item sp
scaled point (65536 @code{sp} = 1 @code{pt})
@end table

@item
If no explicit unit is given, PSPP attempts to guess the best unit:

@itemize @minus
@item
Numbers less than 50 are assumed to be in inches.

@item
Numbers 50 or greater are assumed to be in millimeters.
@end itemize
@end itemize

@node papersize, Distinguishing line types, Dimensions, Output devices
@subsection Paper sizes

Output drivers usually deal with some sort of hardcopy media.  This
media is called @dfn{paper} by the drivers, though in reality it could
be a transparency or film or thinly veiled sarcasm.  To make it easier
for you to deal with paper, PSPP allows you to have (of course!) a
configuration file that gives symbolic names, like ``letter'' or
``legal'' or ``a4'', to paper sizes, rather than forcing you to use
cryptic numbers like ``8-1/2 x 11'' or ``210 by 297''.  Surprisingly
enough, this configuration file is named @file{papersize}.
@xref{Configuration files}.

When PSPP tries to connect a symbolic paper name to a paper size, it
reads and parses each non-comment line in the file, in order.  The first
field on each line must be a symbolic paper name in double quotes.
Paper names may not contain double quotes.  Paper names are not
case-sensitive: @samp{legal} and @samp{Legal} are equivalent.

If a match is found for the paper name, the rest of the line is parsed.
If it is found to be a pair of dimensions (@pxref{Dimensions}) separated
by either @samp{x} or @samp{by}, then those are taken to be the paper
size, in order of width followed by length.  There @emph{must} be at
least one space on each side of @samp{x} or @samp{by}.

Otherwise the line must be of the form
@samp{"@var{paper-1}"="@var{paper-2}"}.  In this case the target of the
search becomes paper name @var{paper-2} and the search through the file
continues.

@node Distinguishing line types, Tokenizing lines, papersize, Output devices
@subsection How lines are divided into types

The lines in @file{devices} are distinguished in the following manner:

@enumerate
@item
Leading white space is removed.

@item
If the resulting line begins with the exact string @code{define},
followed by one or more white space characters, the line is processed as
a macro definition.

@item
Otherwise, the line is scanned for the first instance of a colon
(@samp{:}) or an equals sign (@samp{=}).

@item
If a colon is encountered first, the line is processed as a driver
definition.

@item
Otherwise, if an equals sign is encountered, the line is processed as a
macro definition.

@item
Otherwise, the line is ill-formed.
@end enumerate

@node Tokenizing lines,  , Distinguishing line types, Output devices
@subsection How lines are divided into tokens

Each driver definition line is run through a simple tokenizer.  This
tokenizer recognizes two basic types of tokens.

The first type is an equals sign (@samp{=}).  Equals signs are both
delimiters between tokens and tokens in themselves.

The second type is an identifier or string token.  Identifiers and
strings are equivalent after tokenization, though they are written
differently.  An identifier is any string of characters other than
white space or equals sign.

A string is introduced by a single- or double-quote character (@samp{'}
or @samp{"}) and, in general, continues until the next occurrence of
that same character.  The following standard C escapes can also be
embedded within strings:

@table @code
@item \'
A single-quote (@samp{'}).

@item \"
A double-quote (@samp{"}).

@item \?
A question mark (@samp{?}).  Included for hysterical raisins.

@item \\
A backslash (@samp{\}).

@item \a
Audio bell (ASCII 7).

@item \b
Backspace (ASCII 8).

@item \f
Formfeed (ASCII 12).

@item \n
New-line (ASCII 10)

@item \r
Carriage return (ASCII 13).

@item \t
Tab (ASCII 9).

@item \v
Vertical tab (ASCII 11).

@item \@var{o}@var{o}@var{o}
Each @samp{o} must be an octal digit.  The character is the one having
the octal value specified.  Any number of octal digits is read and
interpreted; only the lower 8 bits are used.

@item \x@var{h}@var{h}
Each @samp{h} must be a hex digit.  The character is the one having the
hexadecimal value specified.  Any number of hex digits is read and
interpreted; only the lower 8 bits are used.
@end table

Tokens, outside of quoted strings, are delimited by white space or equals
signs.

@node PostScript driver class, ASCII driver class, Output devices, Configuration
@section The PostScript driver class

The @code{postscript} driver class is used to produce output that is
acceptable to PostScript printers and to PC-based PostScript
interpreters such as Ghostscript.  Continuing a long tradition,
PSPP's PostScript driver is configurable to the point of
absurdity.

There are actually two PostScript drivers.  The first one,
@samp{postscript}, produces ordinary DSC-compliant PostScript output.
The second one @samp{epsf}, produces an Encapsulated PostScript file.
The two drivers are otherwise identical in configuration and in
operation.

The PostScript driver is described in further detail below.

@menu
* PS output options::           Output file options.
* PS page options::             Paper, margins, scaling & rotation, more!
* PS file options::             Configuration files.
* PS font options::             Default fonts, font options.
* PS line options::             Line widths, options.
* Prologue::                    Details on the PostScript prologue.
* Encodings::                   Details on PostScript font encodings.
@end menu

@node PS output options, PS page options, PostScript driver class, PostScript driver class
@subsection PostScript output options

These options deal with the form of the output and the output file
itself:

@table @code
@item output-file=@var{filename}

File to which output should be sent.  This can be an ordinary filename
(i.e., @code{"pspp.ps"}), a pipe filename (i.e., @code{"|lpr"}), or
stdout (@code{"-"}).  Default: @code{"pspp.ps"}.

@item color=@var{boolean}

Most of the time black-and-white PostScript devices are smart enough to
map colors to shades themselves.  However, you can cause the PSPP
output driver to do an ugly simulation of this in its own driver by
turning @code{color} off.  Default: @code{on}.

This is a boolean setting, as are many settings in the PostScript
driver.  Valid positive boolean values are @samp{on}, @samp{true},
@samp{yes}, and nonzero integers.  Negative boolean values are
@samp{off}, @samp{false}, @samp{no}, and zero.

@item data=@var{data-type}

One of @code{clean7bit}, @code{clean8bit}, or @code{binary}.  This
controls what characters will be written to the output file.  PostScript
produced with @code{clean7bit} can be transmitted over 7-bit
transmission channels that use ASCII control characters for line
control.  @code{clean8bit} is similar but allows characters above 127 to
be written to the output file.  @code{binary} allows any character in
the output file.  Default: @code{clean7bit}.

@item line-ends=@var{line-end-type}

One of @code{cr}, @code{lf}, or @code{crlf}.  This controls what is used
for new-line in the output file.  Default: @code{cr}.

@item optimize-line-size=@var{level}

Either @code{0} or @code{1}.  If @var{level} is @code{1}, then short
line segments will be collected and merged into longer ones.  This
reduces output file size but requires more time and memory.  A
@var{level} of @code{0} has the advantage of being better for
interactive environments.  @code{1} is the default unless the
@code{screen} flag is set; in that case, the default is @code{0}.

@item optimize-text-size=@var{level}

One of @code{0}, @code{1}, or @code{2}, each higher level representing
correspondingly more aggressive space savings for text in the output
file and requiring correspondingly more time and memory.  Unfortunately
the levels presently are all the same.  @code{1} is the default unless
the @code{screen} flag is set; in that case, the default is @code{0}.
@end table

@node PS page options, PS file options, PS output options, PostScript driver class
@subsection PostScript page options

These options affect page setup:

@table @code
@item headers=@var{boolean}

Controls whether the standard headers showing the time and date and
title and subtitle are printed at the top of each page.  Default:
@code{on}.

@item paper-size=@var{paper-size}

Paper size, either as a symbolic name (i.e., @code{letter} or @code{a4})
or specific measurements (i.e., @code{8-1/2x11} or @code{"210 x 297"}.
@xref{papersize, , Paper sizes}.  Default: @code{letter}.

@item orientation=@var{orientation}

Either @code{portrait} or @code{landscape}.  Default: @code{portrait}.

@item left-margin=@var{dimension}
@itemx right-margin=@var{dimension}
@itemx top-margin=@var{dimension}
@itemx bottom-margin=@var{dimension}

Sets the margins around the page.  The headers, if enabled, are not
included in the margins; they are in addition to the margins.  For a
description of dimensions, see @ref{Dimensions}.  Default: @code{0.5in}.

@end table

@node PS file options, PS font options, PS page options, PostScript driver class
@subsection PostScript file options

Oh, my.  You don't really want to know about the way that the PostScript
driver deals with files, do you?  Well I suppose you're entitled, but I
warn you right now: it's not pretty.  Here goes@enddots{}

First let's look at the options that are available:

@table @code

@item font-dir=@var{font-directory}

Sets the font directory.  Default: @code{devps}.

@item prologue-file=@var{prologue-file-name}

Sets the name of the PostScript prologue file.  You can write your own
prologue, though I have no idea why you'd want to: see @ref{Prologue}.
Default: @code{ps-prologue}.

@item device-file=@var{device-file-name}

Sets the name of the Groff-format device description file.  The
PostScript driver reads this to know about the scaling of fonts
and so on.  The format of such files is described in the groff_font man page,
included with Groff.  Default: @code{DESC}.

@item encoding-file=@var{encoding-file-name}

Sets the name of the encoding file.  This file contains a list of all
font encodings that will be needed so that the driver can put all of
them at the top of the prologue.  @xref{Encodings}.  Default:
@code{ps-encodings}.

If the specified encoding file cannot be found, this error will be
silently ignored, since most people do not need any encodings besides
the ones that can be found using @code{auto-encodings}, described below.

@item auto-encode=@var{boolean}

When enabled, the font encodings needed by the default proportional- and
fixed-pitch fonts will automatically be dumped to the PostScript
output.  Otherwise, it is assumed that the user has an encoding file
and knows how to use it (@pxref{Encodings}).  There is probably no good
reason to turn off this convenient feature.  Default: @code{on}.

@end table

Next I suppose it's time to describe the search algorithm.  When the
PostScript driver needs a file, whether that file be a font, a
PostScript prologue, or what you will, it searches in this manner:

@enumerate

@item
Constructs a path by taking the first of the following that is defined:

@enumerate a

@item
Environment variable @code{STAT_GROFF_FONT_PATH}.  @xref{Environment
variables}.

@item
Environment variable @code{GROFF_FONT_PATH}.

@item
The compiled-in fallback default.
@end enumerate

@item
Constructs a base name from concatenating, in order, the font directory,
a path separator (@samp{/} or @samp{\}), and the file to be found.  A
typical base name would be something like @code{devps/ps-encodings}.

@item
Searches for the base name in the path constructed above.  If the file
is found, the algorithm terminates.

@item
Searches for the base name in the standard configuration path.  See
@ref{File locations}, for more details.  If the file is found, the
algorithm terminates.

@item
At this point we remove the font directory and path separator from the
base name.  Now the base name is simply the file to be found, i.e.,
@code{ps-encodings}.

@item
Searches for the base name in the path constructed in the first step.
If the file is found, the algorithm terminates.

@item
Searches for the base name in the standard configuration path.  If the
file is found, the algorithm terminates.

@item
The algorithm terminates unsuccessfully.
@end enumerate

So, as you see, there are several ways to configure the PostScript
drivers.  Careful selection of techniques can make the configuration
very flexible indeed.

@node PS font options, PS line options, PS file options, PostScript driver class
@subsection PostScript font options

The list of available font options is short and sweet:

@table @code
@item prop-font=@var{font-name}

Sets the default proportional font.  The name should be that of a
PostScript font.  Default: @code{"Helvetica"}.

@item fixed-font=@var{font-name}

Sets the default fixed-pitch font.  The name should be that of a
PostScript font.  Default: @code{"Courier"}.

@item font-size=@var{font-size}

Sets the size of the default fonts, in thousandths of a point.  Default:
@code{10000}.

@end table

@node PS line options, Prologue, PS font options, PostScript driver class
@subsection PostScript line options

Most tables contain lines, or rules, between cells.  Some features of
the way that lines are drawn in PostScript tables are user-definable:

@table @code

@item line-style=@var{style}

Sets the style used for lines used to divide tables into sections.
@var{style} must be either @code{thick}, in which case thick lines are
used, or @var{double}, in which case double lines are used.  Default:
@code{thick}.

@item line-gutter=@var{dimension}

Sets the line gutter, which is the amount of white space on either side
of lines that border text or graphics objects.  @xref{Dimensions}.
Default: @code{0.5pt}.

@item line-spacing=@var{dimension}

Sets the line spacing, which is the amount of white space that separates
lines that are side by side, as in a double line.  Default:
@code{0.5pt}.

@item line-width=@var{dimension}

Sets the width of a typical line used in tables.  Default: @code{0.5pt}.

@item line-width-thick=@var{dimension}

Sets the width of a thick line used in tables.  Not used if
@code{line-style} is set to @code{thick}.  Default: @code{1.5pt}.

@end table

@node Prologue, Encodings, PS line options, PostScript driver class
@subsection The PostScript prologue

Most PostScript files that are generated mechanically by programs
consist of two parts: a prologue and a body.  The prologue is generally
a collection of boilerplate.  Only the body differs greatly between
two outputs from the same program.
 
This is also the strategy used in the PSPP PostScript driver.  In
general, the prologue supplied with PSPP will be more than sufficient.
In this case, you will not need to read the rest of this section.
However, hackers might want to know more.  Read on, if you fall into
this category.

The prologue is dumped into the output stream essentially unmodified.
However, two actions are performed on its lines.  First, certain lines
may be omitted as specified in the prologue file itself.  Second,
variables are substituted.

The following lines are omitted:

@enumerate
@item
All lines that contain three bangs in a row (@code{!!!}).

@item
Lines that contain @code{!eps}, if the PostScript driver is producing
ordinary PostScript output.  Otherwise an EPS file is being produced,
and the line is included in the output, although everything following
@code{!eps} is deleted.

@item
Lines that contain @code{!ps}, if the PostScript driver is producing EPS
output.  Otherwise, ordinary PostScript is being produced, and the line
is included in the output, although everything following @code{!ps} is
deleted.
@end enumerate

The following are the variables that are substituted.  Only the
variables listed are substituted; environment variables are not.
@xref{Environment substitutions}.

@table @code
@item bounding-box

The page bounding box, in points, as four space-separated numbers.  For
U.S. letter size paper, this is @samp{0 0 612 792}.

@item creator

PSPP version as a string: @samp{GNU PSPP 0.1b}, for example.

@item date

Date the file was created.  Example: @samp{Tue May 21 13:46:22 1991}.

@item data

Value of the @code{data} PostScript driver option, as one of the strings
@samp{Clean7Bit}, @samp{Clean8Bit}, or @samp{Binary}.

@item orientation

Page orientation, as one of the strings @code{Portrait} or
@code{Landscape}.

@item user

Under multiuser OSes, the user's login name, taken either from the
environment variable @code{LOGNAME} or, if that fails, the result of the
C library function @code{getlogin()}.  Defaults to @samp{nobody}.

@item host

System hostname as reported by @code{gethostname()}.  Defaults to
@samp{nowhere}.

@item prop-font

Name of the default proportional font, prefixed by the word
@samp{font} and a space.  Example: @samp{font Times-Roman}.

@item fixed-font

Name of the default fixed-pitch font, prefixed by the word @samp{font}
and a space.

@item scale-factor

The page scaling factor as a floating-point number.  Example:
@code{1.0}.  Note that this is also passed as an argument to the BP
macro.

@item paper-length
@item paper-width

The paper length and paper width, respectively, in thousandths of a
point.  Note that these are also passed as arguments to the BP macro.

@item left-margin
@item top-margin

The left margin and top margin, respectively, in thousandths of a
point.  Note that these are also passed as arguments to the BP macro.

@item title

Document title as a string.  This is not the title specified in the
PSPP syntax file.  A typical title is the word @samp{PSPP} followed
by the syntax file name in parentheses.  Example: @samp{PSPP
(<stdin>)}.

@item source-file

PSPP syntax file name.  Example: @samp{mary96/first.stat}.

@end table

Any other questions about the PostScript prologue can best be answered
by examining the default prologue or the PSPP source.

@node Encodings,  , Prologue, PostScript driver class
@subsection PostScript encodings

PostScript fonts often contain many more than 256 characters, in order
to accommodate foreign language characters and special symbols.
PostScript uses @dfn{encodings} to map these onto single-byte symbol
sets.  Each font can have many different encodings applied to it.

PSPP's PostScript driver needs to know which encoding to apply to each
font.  It can determine this from the information encapsulated in the
Groff font description that it reads.  However, there is an additional
problem---for efficiency, the PostScript driver needs to have a complete
list of all encodings that will be used in the entire session @emph{when
it opens the output file}.  For this reason, it can't use the
information built into the fonts because it doesn't know which fonts
will be used.

As a stopgap solution, there are two mechanisms for specifying which
encodings will be used.  The first mechanism is automatic and it is the
only one that most PSPP users will ever need.  The second mechanism is
manual, but it is more flexible.  Either mechanism or both may be used
at one time.

The first mechanism is activated by the @samp{auto-encode} driver option
(@pxref{PS file options}).  When enabled, @samp{auto-encode} causes the
PostScript driver to include the encodings used by the default
proportional and fixed-pitch fonts (@pxref{PS font options}).  Many
PSPP output files will only need these encodings.

The second mechanism is the file specified by the @samp{encoding-file}
option (@pxref{PS file options}).  If it exists, this file must consist
of lines in PSPP configuration-file format (@pxref{Configuration
files}).  Each line that is not a comment should name a PostScript
encoding to include in the output.

It is not an error if an encoding is included more than once, by either
mechanism.  It will appear only once in the output.  It is also not an
error if an encoding is included in the output but never used.  It
@emph{is} an error if an encoding is used but not included by one of
these mechanisms.  In this case, the built-in PostScript encoding
@samp{ISOLatin1Encoding} is substituted.

@node ASCII driver class, HTML driver class, PostScript driver class, Configuration
@section The ASCII driver class

The ASCII driver class produces output that can be displayed on a
terminal or output to printers.  All of its options are highly
configurable.  The ASCII driver has class name @samp{ascii}.

The ASCII driver is described in further detail below.

@menu
* ASCII output options::        Output file options.
* ASCII page options::          Page size, margins, more.
* ASCII font options::          Box character, bold & italics.
@end menu

@node ASCII output options, ASCII page options, ASCII driver class, ASCII driver class
@subsection ASCII output options

@table @code
@item output-file=@var{filename}

File to which output should be sent.  This can be an ordinary filename
(e.g., @code{"pspp.txt"}), a pipe filename (e.g., @code{"|lpr"}), or
stdout (@code{"-"}).  Default: @code{"pspp.list"}.

@item char-set=@var{char-set-type}

One of @samp{ascii} or @samp{latin1}.  This has no effect on output at
the present time.  Default: @code{ascii}.

@item form-feed-string=@var{form-feed-value}

The string written to the output to cause a formfeed.  See also
@code{paginate}, described below, for a related setting.  Default:
@code{"\f"}.

@item newline-string=@var{new-line-value}

The string written to the output to cause a new-line (carriage return
plus linefeed).  The default, which can be specified explicitly with
@code{newline-string=default}, is to use the system-dependent new-line
sequence by opening the output file in text mode.  This is usually the
right choice.

However, @code{newline-string} can be set to any string.  When this is
done, the output file is opened in binary mode.

@item paginate=@var{boolean}

If set, a formfeed (as set in @code{form-feed-string}, described above)
will be written to the device after every page.  Default: @code{on}.

@item tab-width=@var{tab-width-value}

The distance between tab stops for this device.  If set to 0, tabs will
not be used in the output.  Default: @code{8}.

@item init=@var{initialization-string}.

String written to the device before anything else, at the beginning of
the output.  Default: @code{""} (the empty string).

@item done=@var{finalization-string}.

String written to the device after everything else, at the end of the
output.  Default: @code{""} (the empty string).
@end table

@node ASCII page options, ASCII font options, ASCII output options, ASCII driver class
@subsection ASCII page options

These options affect page setup:

@table @code
@item headers=@var{boolean}

If enabled, two lines of header information giving title and subtitle,
page number, date and time, and PSPP version are printed at the top of
every page.  These two lines are in addition to any top margin
requested.  Default: @code{on}.

@item length=@var{line-count}

Physical length of a page, in lines.  Headers and margins are subtracted
from this value.  Default: @code{66}.

@item width=@var{character-count}

Physical width of a page, in characters.  Margins are subtracted from
this value.  Default: @code{130}.

@item lpi=@var{lines-per-inch}

Number of lines per vertical inch.  Not currently used.  Default: @code{6}.

@item cpi=@var{characters-per-inch}

Number of characters per horizontal inch.  Not currently used.  Default:
@code{10}.

@item left-margin=@var{left-margin-width}

Width of the left margin, in characters.  PSPP subtracts this value
from the page width.  Default: @code{0}.

@item right-margin=@var{right-margin-width}

Width of the right margin, in characters.  PSPP subtracts this value
from the page width.  Default: @code{0}.

@item top-margin=@var{top-margin-lines}

Length of the top margin, in lines.  PSPP subtracts this value from
the page length.  Default: @code{2}.

@item bottom-margin=@var{bottom-margin-lines}

Length of the bottom margin, in lines.  PSPP subtracts this value from
the page length.  Default: @code{2}.

@end table

@node ASCII font options,  , ASCII page options, ASCII driver class
@subsection ASCII font options

These are the ASCII font options:

@table @code
@item box[@var{line-type}]=@var{box-chars}

The characters used for lines in tables produced by the ASCII driver can
be changed using this option.  @var{line-type} is used to indicate which
type of line to change; @var{box-chars} is the character or string of
characters to use for this type of line.

@var{line-type} must be a 4-digit number in base 4.  The digits are in
the order `right', `bottom', `left', `top'.  The four possibilities for
each digit are:

@table @asis
@item 0
No line.

@item 1
Single line.

@item 2
Double line.

@item 3
Special device-defined line, if one is available; otherwise, a double
line.
@end table

Examples:

@table @code
@item box[0101]="|"

Sets @samp{|} as the character to use for a single-width line with
bottom and top components.

@item box[2222]="#"

Sets @samp{#} as the character to use for the intersection of four
double-width lines, one each from the top, bottom, left and right.

@item box[1100]="\xda"

Sets @samp{"\xda"}, which under MS-DOS is a box character suitable for
the top-left corner of a box, as the character for the intersection of
two single-width lines, one each from the right and bottom.

@end table

Defaults:

@itemize @bullet
@item
@code{box[0000]=" "}

@item
@code{box[1000]="-"}
@*@code{box[0010]="-"}
@*@code{box[1010]="-"}

@item
@code{box[0100]="|"}
@*@code{box[0001]="|"}
@*@code{box[0101]="|"}

@item
@code{box[2000]="="}
@*@code{box[0020]="="}
@*@code{box[2020]="="}

@item
@code{box[0200]="#"}
@*@code{box[0002]="#"}
@*@code{box[0202]="#"}

@item
@code{box[3000]="="}
@*@code{box[0030]="="}
@*@code{box[3030]="="}

@item
@code{box[0300]="#"}
@*@code{box[0003]="#"}
@*@code{box[0303]="#"}

@item
For all others, @samp{+} is used unless there are double lines or
special lines, in which case @samp{#} is used.
@end itemize

@item italic-on=@var{italic-on-string}

Character sequence written to turn on italics or underline printing.  If
this is set to @code{overstrike}, then the driver will simulate
underlining by overstriking with underscore characters (@samp{_}) in the
manner described by @code{overstrike-style} and
@code{carriage-return-style}.  Default: @code{overstrike}.

@item italic-off=@var{italic-off-string}

Character sequence to turn off italics or underline printing.  Default:
@code{""} (the empty string).

@item bold-on=@var{bold-on-string}

Character sequence written to turn on bold or emphasized printing.  If
set to @code{overstrike}, then the driver will simulated bold printing
by overstriking characters in the manner described by
@code{overstrike-style} and @code{carriage-return-style}.  Default:
@code{overstrike}.

@item bold-off=@var{bold-off-string}

Character sequence to turn off bold or emphasized printing.  Default:
@code{""} (the empty string).

@item bold-italic-on=@var{bold-italic-on-string}

Character sequence written to turn on bold-italic printing.  If set to
@code{overstrike}, then the driver will simulate bold-italics by
overstriking twice, once with the character, a second time with an
underscore (@samp{_}) character, in the manner described by
@code{overstrike-style} and @code{carriage-return-style}.  Default:
@code{overstrike}.

@item bold-italic-off=@var{bold-italic-off-string}

Character sequence to turn off bold-italic printing.  Default: @code{""}
(the empty string).

@item overstrike-style=@var{overstrike-option}

Either @code{single} or @code{line}:

@itemize @bullet
@item
If @code{single} is selected, then, to overstrike a line of text, the
output driver will output a character, backspace, overstrike, output a
character, backspace, overstrike, and so on along a line.

@item
If @code{line} is selected then the output driver will output an entire
line, then backspace or emit a carriage return (as indicated by
@code{carriage-return-style}), then overstrike the entire line at once.
@end itemize

@code{single} is recommended for use with ttys and programs that
understand overstriking in text files, such as the pager @code{less}.
@code{single} will also work with printer devices but results in rapid
back-and-forth motions of the printhead that can cause the printer to
physically overheat!

@code{line} is recommended for use with printer devices.  Most programs
that understand overstriking in text files will not properly deal with
@code{line} mode.  

Default: @code{single}.

@item carriage-return-style=@var{carriage-return-type}

Either @code{bs} or @code{cr}.  This option applies only when one or
more of the font commands is set to @code{overstrike} and, at the same
time, @code{overstrike-style} is set to @code{line}.

@itemize @bullet
@item
If @code{bs} is selected then the driver will return to the beginning of
a line by emitting a sequence of backspace characters (ASCII 8).

@item
If @code{cr} is selected then the driver will return to the beginning of
a line by emitting a single carriage-return character (ASCII 13).
@end itemize

Although @code{cr} is preferred as being more compact, @code{bs} is more
general since some devices do not interpret carriage returns in the
desired manner.  Default: @code{bs}.
@end table

@node HTML driver class, Miscellaneous configuring, ASCII driver class, Configuration
@section The HTML driver class

The @code{html} driver class is used to produce output for viewing in
tables-capable web browsers such as Emacs' w3-mode.  Its configuration
is very simple.  Currently, the output has a very plain format.  In the
future, further work may be done on improving the output appearance.

There are few options for use with the @code{html} driver class:

@table @code
@item output-file=@var{filename}

File to which output should be sent.  This can be an ordinary filename
(i.e., @code{"pspp.ps"}), a pipe filename (i.e., @code{"|lpr"}), or
stdout (@code{"-"}).  Default: @code{"pspp.html"}.

@item prologue-file=@var{prologue-file-name}

Sets the name of the PostScript prologue file.  You can write your own
prologue if you want to customize colors or other settings: see
@ref{HTML Prologue}.  Default: @code{html-prologue}.
@end table

@menu
* HTML Prologue::               Format of the HTML prologue file.
@end menu

@node HTML Prologue,  , HTML driver class, HTML driver class
@subsection The HTML prologue

HTML files that are generated by PSPP consist of two parts: a prologue
and a body.  The prologue is a collection of boilerplate.  Only the body
differs greatly between two outputs.  You can tune the colors and other
attributes of the output by editing the prologue.
 
The prologue is dumped into the output stream essentially unmodified.
However, two actions are performed on its lines.  First, certain lines
may be omitted as specified in the prologue file itself.  Second,
variables are substituted.

The following lines are omitted:

@enumerate
@item
All lines that contain three bangs in a row (@code{!!!}).

@item
Lines that contain @code{!title}, if no title is set for the output.  If
a title is set, then the characters @code{!title} are removed before the
line is output.

@item
Lines that contain @code{!subtitle}, if no subtitle is set for the
output.  If a subtitle is set, then the characters @code{!subtitle} are
removed before the line is output.
@end enumerate

The following are the variables that are substituted.  Only the
variables listed are substituted; environment variables are not.
@xref{Environment substitutions}.

@table @code
@item generator

PSPP version as a string: @samp{GNU PSPP 0.1b}, for example.

@item date

Date the file was created.  Example: @samp{Tue May 21 13:46:22 1991}.

@item user

Under multiuser OSes, the user's login name, taken either from the
environment variable @code{LOGNAME} or, if that fails, the result of the
C library function @code{getlogin()}.  Defaults to @samp{nobody}.

@item host

System hostname as reported by @code{gethostname()}.  Defaults to
@samp{nowhere}.

@item title

Document title as a string.  This is the title specified in the PSPP
syntax file.

@item subtitle

Document subtitle as a string.  

@item source-file

PSPP syntax file name.  Example: @samp{mary96/first.stat}.
@end table

@node Miscellaneous configuring, Improving output quality, HTML driver class, Configuration
@section Miscellaneous configuration

The following environment variables can be used to further configure
PSPP:

@table @code
@item HOME

Used to determine the user's home directory.  No default value.

@item STAT_INCLUDE_PATH

Path used to find include files in PSPP syntax files.  Defaults vary
across operating systems:

@table @asis
@item UNIX

@itemize @bullet
@item
@file{.}

@item
@file{~/.pspp/include}

@item
@file{/usr/local/lib/pspp/include}

@item
@file{/usr/lib/pspp/include}

@item
@file{/usr/local/share/pspp/include}

@item
@file{/usr/share/pspp/include}
@end itemize

@item MS-DOS

@itemize @bullet
@item
@file{.}

@item
@file{C:\PSPP\INCLUDE}

@item
@file{$PATH}
@end itemize

@item Other OSes
No default path.
@end table

@item TERM

The terminal type @code{termcap} or @code{ncurses} will use, if such
support was compiled into PSPP.

@item STAT_OUTPUT_INIT_FILE

The basename used to search for the driver definition file.
@xref{Output devices}.  @xref{File locations}.  Default: @code{devices}.

@item STAT_OUTPUT_PAPERSIZE_FILE

The basename used to search for the papersize file.  @xref{papersize}.
@xref{File locations}.  Default: @code{papersize}.

@item STAT_OUTPUT_INIT_PATH

The path used to search for the driver definition file and the papersize
file.  @xref{File locations}.  Default: the standard configuration path.

@item TMPDIR

The directory in which PSPP stores its temporary files (used when sorting 
cases or concatenating large numbers of cases).
Default: (UNIX) @file{/tmp}, (MS-DOS) @file{\}, (other OSes) empty string.

@item TEMP
@item TMP

Under MS-DOS only, these variables are consulted after TMPDIR, in this
order.
@end table

@node Improving output quality,  , Miscellaneous configuring, Configuration
@section Improving output quality

When its drivers are set up properly, PSPP can produce output that
looks very good indeed.  The PostScript driver, suitably configured, can
produce presentation-quality output.  Here are a few guidelines for
producing better-looking output, regardless of output driver.  Your
mileage may vary, of course, and everyone has different esthetic
preferences.

@itemize @bullet
@item
Width is important in PSPP output.  Greater output width leads to more
readable output, to a point.  Try the following to increase the output
width:

@itemize @minus
@item
If you're using the ASCII driver with a dot-matrix printer, figure out
what you need to do to put the printer into compressed mode.  Put that
string into the @code{init-string} setting.  Try to get 132 columns; 160
might be better, but you might find that print that tiny is difficult to
read.

@item
With the PostScript driver, try these ideas:

@itemize +
@item
Landscape mode.

@item
Legal-size (8.5" x 14") paper in landscape mode.

@item
Reducing font sizes.  If you're using 12-point fonts, try 10 point; if
you're using 10-point fonts, try 8 point.  Some fonts are more readable
than others at small sizes.
@end itemize
@end itemize

Try to strike a balance between character size and page width.

@item
Use high-quality fonts.  Many public domain fonts are poor in quality.
Recently, URW made some high-quality fonts available under the GPL.
These are probably suitable.

@item
Be sure you're using the proper font metrics.  The font metrics provided
with PSPP may not correspond to the fonts actually being printed.
This can cause bizarre-looking output.

@item
Make sure that you're using good ink/ribbon/toner.  Darker print is
easier to read.

@item
Use plain fonts with serifs, such as Times-Roman or Palatino.  Avoid
choosing italic or bold fonts as document base fonts.
@end itemize
@setfilename ignored