means-calc.c: Add comments where needed.

[pspp] / doc / dev / system-file-format.texi

diff --git a/doc/dev/system-file-format.texi b/doc/dev/system-file-format.texi
index e52b9571166a25b477a8f6263f34d0960b9f0423..500d74f66556fcff16d9ef14cf547a2375b8ee2e 100644 (file)
--- a/doc/dev/system-file-format.texi
+++ b/doc/dev/system-file-format.texi
@@ -222,6 +222,12 @@ pspp 0.1.4 - sparc-sun-solaris2.5.2}.  The string is truncated if it
 would be longer than 60 characters; otherwise it is padded on the right
 with spaces.
 
 would be longer than 60 characters; otherwise it is padded on the right
 with spaces.
 

+The product name field allow readers to behave differently based on
+quirks in the way that particular software writes system files.
+@xref{Value Labels Records}, for the detail of the quirk that the PSPP
+system file reader tolerates in files written by ReadStat, which has
+@code{https://github.com/WizardMac/ReadStat} in @code{prod_name}.
+

 @anchor{layout_code}
 @item int32 layout_code;
 Normally set to 2, although a few system files have been spotted in
 @anchor{layout_code}
 @item int32 layout_code;
 Normally set to 2, although a few system files have been spotted in


@@ -310,10 +316,10 @@ so readers should take care to parse dummy variable records in the
 same way as other variable records.
 
 @anchor{Dictionary Index}
 same way as other variable records.
 
 @anchor{Dictionary Index}

-The @dfn{dictionary index} of a variable is its offset in the set of
+The @dfn{dictionary index} of a variable is a 1-based offset in the set of

 variable records, including dummy variable records for long string
 variable records, including dummy variable records for long string

-variables.  The first variable record has a dictionary index of 0, the
-second has a dictionary index of 1, and so on.
+variables.  The first variable record has a dictionary index of 1, the
+second has a dictionary index of 2, and so on.

 
 The system file format does not directly support string variables
 wider than 255 bytes.  Such very long string variables are represented
 
 The system file format does not directly support string variables
 wider than 255 bytes.  Such very long string variables are represented


@@ -508,6 +514,10 @@ Format types are defined as follows:
 @tab @code{EDATE}
 @item 39
 @tab @code{SDATE}
 @tab @code{EDATE}
 @item 39
 @tab @code{SDATE}

+@item 40
+@tab @code{MTIME}
+@item 41
+@tab @code{YMDHMS}

 @end multitable
 @end quotation
 
 @end multitable
 @end quotation
 


@@ -524,6 +534,14 @@ numeric and short string variables only.  Long string variables may
 have value labels, but their value labels are recorded using a
 different record type (@pxref{Long String Value Labels Record}).
 
 have value labels, but their value labels are recorded using a
 different record type (@pxref{Long String Value Labels Record}).
 

+ReadStat (@pxref{File Header Record}) writes value labels that label a
+single value more than once.  In more detail, it emits value labels
+whose values are longer than string variables' widths, that are
+identical in the actual width of the variable, e.g.@: labels for
+values @code{ABC123} and @code{ABC456} for a string variable with
+width 3.  For files written by this software, PSPP ignores such
+labels.
+

 The value label record has the following format:
 
 @example
 The value label record has the following format:
 
 @example


@@ -582,7 +600,7 @@ Number of variables that the associated value labels from the value
 label record are to be applied.
 
 @item int32 vars[];
 label record are to be applied.
 
 @item int32 vars[];

-A list of dictionary indexes of variables to which to apply the value
+A list of 1-based dictionary indexes of variables to which to apply the value

 labels (@pxref{Dictionary Index}).  There are @code{var_count}
 elements.
 
 labels (@pxref{Dictionary Index}).  There are @code{var_count}
 elements.
 


@@ -606,9 +624,7 @@ Record type.  Always set to 6.
 
 @item int32 n_lines;
 Number of lines of documents present.  This should be greater than
 
 @item int32 n_lines;
 Number of lines of documents present.  This should be greater than

-zero, but the system file writer that identifies itself as
-@url{https://github.com/WizardMac/ReadStat} writes document records
-with zero @code{n_lines}.
+zero, but ReadStats writes system files with zero @code{n_lines}.

 
 @item char lines[][80];
 Document lines.  The number of elements is defined by @code{n_lines}.
 
 @item char lines[][80];
 Document lines.  The number of elements is defined by @code{n_lines}.


@@ -1560,9 +1576,10 @@ value @var{code} - @var{bias}, where
 variable @code{bias} from the file header.  For example,
 code 105 with bias 100.0 (the normal value) indicates a numeric variable
 of value 5.
 variable @code{bias} from the file header.  For example,
 code 105 with bias 100.0 (the normal value) indicates a numeric variable
 of value 5.

-One file has been seen written by SPSS 14 that contained such a code
-in a @emph{string} field with the value 0 (after the bias is
-subtracted) as a way of encoding null bytes.
+
+A code of 0 (after subtracting the bias) in a string field encodes
+null bytes.  This is unusual, since a string field normally encodes
+text data, but it exists in real system files.

 
 @item 252
 End of file.  This code may or may not appear at the end of the data
 
 @item 252
 End of file.  This code may or may not appear at the end of the data