* Missing Observations:: Handling missing observations.
* Variables:: The unit of data storage.
* Files:: Files used by PSPP.
+* File Handles:: How files are named.
* BNF:: How command syntax is described.
@end menu
to copy its value into an ordinary variable, then use that ordinary
variable in the analysis.
-@node Files, BNF, Variables, Language
+@node Files
@section Files Used by PSPP
PSPP makes use of many files each time it runs. Some of these it
@itemx syntax file
These names (synonyms) refer to the file that contains instructions
that tell PSPP what to do. The syntax file's name is specified on
-the PSPP command line. Syntax files can also be pulled in with
+the PSPP command line. Syntax files can also be read with
@cmd{INCLUDE} (@pxref{INCLUDE}).
@cindex file, data
@cindex data file
@item data file
-Data files contain raw data in ASCII format suitable for being read in
-by @cmd{DATA LIST}. Data can be embedded in the syntax
-file with @cmd{BEGIN DATA} and @cmd{END DATA}: this makes the
-syntax file a data file too.
+Data files contain raw data in text or binary format. Data can also
+be embedded in a syntax file with @cmd{BEGIN DATA} and @cmd{END DATA}.
@cindex file, output
@cindex output file
@cindex active file
@cindex file, active
@item active file
-The active file is the ``file'' on which all PSPP procedures
-are performed. The active file contains variable definitions and
-cases. The active file is not necessarily a disk file: it is stored
-in memory if there is room.
+The active file is the ``file'' on which all PSPP procedures are
+performed. The active file consists of a dictionary and a set of cases.
+The active file is not necessarily a disk file: it is stored in memory
+if there is room.
+
+@cindex system file
+@cindex file, system
+@item system file
+System files are binary files that store a dictionary and a set of
+cases. @cmd{GET} and @cmd{SAVE} read and write system files.
+
+@cindex portable file
+@cindex file, portable
+@item portable file
+Portable files are files in a text-based format that store a dictionary
+and a set of cases. @cmd{IMPORT} and @cmd{EXPORT} read and write
+portable files.
+
+@cindex scratch file
+@cindex file, scratch
+@item scratch file
+Scratch files consist of a dictionary and cases and may be stored in
+memory or on disk. Most procedures that act on a system file or
+portable file can use a scratch file instead. The contents of scratch
+files persist within a single PSPP session only. @cmd{GET} and
+@cmd{SAVE} can be used to read and write scratch files. Scratch files
+are a PSPP extension.
@end table
-@node BNF, , Files, Language
+@node File Handles
+@section File Handles
+@cindex file handles
+
+A @dfn{file handle} is a reference to a data file, system file, portable
+file, or scratch file. Most often, a file handle is specified as the
+name of a file as a string, that is, enclosed within @samp{'} or
+@samp{"}.
+
+PSPP also supports declaring named file handles with the @cmd{FILE
+HANDLE} command. This command associates an identifier of your choice
+(the file handle's name) with a file. Later, the file handle name can
+be substituted for the name of the file. When PSPP syntax accesses a
+file multiple times, declaring a named file handle simplifies updating
+the syntax later to use a different file. Use of @cmd{FILE HANDLE} is
+also required to read data files in binary formats. @xref{FILE HANDLE},
+for more information.
+
+PSPP assumes that a file handle name that begins with @samp{#} refers to
+a scratch file, unless the name has already been declared on @cmd{FILE
+HANDLE} to refer to another kind of file. A scratch file is similar to
+a system file, except that it persists only for the duration of a given
+PSPP session. Most commands that read or write a system or portable
+file, such as @cmd{GET} and @cmd{SAVE}, also accept scratch file
+handles. Scratch file handles may also be declared explicitly with
+@cmd{FILE HANDLE}. Scratch files are a PSPP extension.
+
+In some circumstances, PSPP must distinguish whether a file handle
+refers to a system file or a portable file. When this is necessary to
+read a file, e.g.@: as an input file for @cmd{GET} or @cmd{MATCH FILES},
+PSPP uses the file's contents to decide. In the context of writing a
+file, e.g.@: as an output file for @cmd{SAVE} or @cmd{AGGREGATE}, PSPP
+decides based on the file's name: if it ends in @samp{.por} (with any
+capitalization), then PSPP writes a portable file; otherwise, PSPP
+writes a system file.
+
+INLINE is reserved as a file handle name. It refers to the ``data
+file'' embedded into the syntax file between @cmd{BEGIN DATA} and
+@cmd{END DATA}. @xref{BEGIN DATA}, for more information.
+
+The file to which a file handle refers may be reassigned on a later
+@cmd{FILE HANDLE} command if it is first closed using @cmd{CLOSE FILE
+HANDLE}. The @cmd{CLOSE FILE HANDLE} command is also useful to free the
+storage associated with a scratch file. @xref{CLOSE FILE HANDLE}, for
+more information.
+
+@node BNF
@section Backus-Naur Form
@cindex BNF
@cindex Backus-Naur Form
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