X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fcombining.texi;h=ad2ed03e3fddfe0929167db1540aa61066174e90;hb=5204698c0d3a9bd3786d8bd19eba2a1ddbbb4311;hp=00f6067a98aa7b2967d62e2e86806c654db1cbab;hpb=1b1837591924226078c96db15888b68beec2ef6d;p=pspp

diff --git a/doc/combining.texi b/doc/combining.texi
index 00f6067a98..ad2ed03e3f 100644
--- a/doc/combining.texi
+++ b/doc/combining.texi
@@ -1,3 +1,12 @@
+@c PSPP - a program for statistical analysis.
+@c Copyright (C) 2017 Free Software Foundation, Inc.
+@c Permission is granted to copy, distribute and/or modify this document
+@c under the terms of the GNU Free Documentation License, Version 1.3
+@c or any later version published by the Free Software Foundation;
+@c with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
+@c A copy of the license is included in the section entitled "GNU
+@c Free Documentation License".
+@c
 @node Combining Data Files
 @chapter Combining Data Files
 
@@ -58,9 +67,11 @@ This section describes the syntactical features in common among the
 @cmd{ADD FILES}, @cmd{MATCH FILES}, and @cmd{UPDATE} commands.  The
 following sections describe details specific to each command.
 
-Each of these commands reads two or more input files and combines
-them.  The command's output becomes the new active dataset.  The input
-files are not changed on disk.
+Each of these commands reads two or more input files and combines them.  
+The command's output becomes the new active dataset.
+None of the commands actually change the input files.
+Therefore, if you want the changes to become permanent, you must explicitly
+save them using an appropriate procedure or transformation (@pxref{System and Portable File IO}).
 
 The syntax of each command begins with a specification of the files to
 be read as input.  For each input file, specify FILE with a system
@@ -117,7 +128,7 @@ similarly for value labels and missing values.
 
 @item
 The file label of the new active dataset (@pxref{FILE LABEL}) is that of the
-first specified FILE that has a file label.
+first specified @subcmd{FILE} that has a file label.
 
 @item
 The documents in the new active dataset (@pxref{DOCUMENT}) are the
@@ -132,7 +143,7 @@ active dataset is not weighted.
 
 The remaining subcommands apply to the output file as a whole, rather
 than to individual input files.  They must be specified at the end of
-the command specification, following all of the FILE and related
+the command specification, following all of the @subcmd{FILE} and related
 subcommands.  The most important of these subcommands is @subcmd{BY}, which
 specifies a set of one or more variables that may be used to find
 corresponding cases in each of the input files.  The variables
@@ -168,6 +179,9 @@ only in files that are not present for the current case are set to the
 system-missing value for numeric variables or spaces for string
 variables.
 
+These commands may combine any number of files, limited only by the
+machine's memory.
+
 @node ADD FILES
 @section ADD FILES
 @vindex ADD FILES
@@ -250,7 +264,7 @@ to cases output after their input has been exhausted.
 
 @item
 If @subcmd{BY} is used, @cmd{MATCH FILES} combines cases from each input file that
-have identical values for the BY variables.
+have identical values for the @subcmd{BY} variables.
 
 When @subcmd{BY} is used, @subcmd{TABLE} subcommands may be used to introduce @dfn{table
 lookup file}.  @subcmd{TABLE} has same syntax as @subcmd{FILE}, and the @subcmd{RENAME}, @subcmd{IN}, and
@@ -315,14 +329,14 @@ case in the master file:
 @itemize @bullet
 @item
 When a match is found, then the values of the variables present in the
-transaction file replace those variable's values in the new active
+transaction file replace those variables' values in the new active
 file.  If there are matching cases in more than more transaction file,
 @pspp{} applies the replacements from the first transaction file, then
 from the second transaction file, and so on.  Similarly, if a single
 transaction file has cases with duplicate @subcmd{BY} values, then those are
 applied in order to the master file.
 
-When a variable in a transaction file has a missing value or a string
+When a variable in a transaction file has a missing value or when a string
 variable's value is all blanks, that value is never used to update the
 master file.