that describes how they may be interpreted. This chapter describes
the format of a system file.
-System files use three data types: 8-bit characters, 32-bit integers,
-and 64-bit floating points, called here @code{char}, @code{int32}, and
+System files use four data types: 8-bit characters, 32-bit integers,
+64-bit integers,
+and 64-bit floating points, called here @code{char}, @code{int32},
+@code{int64}, and
@code{flt64}, respectively. Data is not necessarily aligned on a word
or double-word boundary: the long variable name record (@pxref{Long
Variable Names Record}) and very long string records (@pxref{Very Long
Document record, if present.
@item
-Any of the following records, if present, in any order:
-
-@itemize @minus
-@item
-Machine integer info record.
-
-@item
-Machine floating-point info record.
-
-@item
-Variable display parameter record.
-
-@item
-Long variable names record.
-
-@item
-Miscellaneous informational records.
-@end itemize
+Any records not explicitly included in this list, in any order.
@item
Dictionary termination record.
* Character Encoding Record::
* Long String Value Labels Record::
* Data File and Variable Attributes Records::
+* Extended Number of Cases Record::
* Miscellaneous Informational Records::
* Dictionary Termination Record::
* Data Record::
that will be output to a system file at the time that the header is
written. The way that this is dealt with is by writing the entire
system file, including the header, then seeking back to the beginning of
-the file and writing just the @code{ncases} field. For `files' in which
+the file and writing just the @code{ncases} field. For files in which
this is not valid, the seek operation fails. In this case,
@code{ncases} remains -1.
The first @code{label_len} characters are the variable's variable label.
@item flt64 missing_values[];
-This field is present only if @code{n_missing_values} is not 0. It has
-the same number of elements as the absolute value of
-@code{n_missing_values}. For discrete missing values, each element
-represents one missing value. When a range is present, the first
-element denotes the minimum value in the range, and the second element
-denotes the maximum value in the range. When a range plus a value are
-present, the third element denotes the additional discrete missing
-value. HIGHEST and LOWEST are indicated as described in the chapter
-introduction.
+This field is present only if @code{n_missing_values} is nonzero. It
+has the same number of 8-byte elements as the absolute value of
+@code{n_missing_values}. Each element is interpreted as a number for
+numeric variables (with HIGHEST and LOWEST indicated as described in
+the chapter introduction). For string variables of width less than 8
+bytes, elements are right-padded with spaces; for string variables
+wider than 8 bytes, only the first 8 bytes of each missing value are
+specified, with the remainder implicitly all spaces.
+
+For discrete missing values, each element represents one missing
+value. When a range is present, the first element denotes the minimum
+value in the range, and the second element denotes the maximum value
+in the range. When a range plus a value are present, the third
+element denotes the additional discrete missing value.
@end table
The @code{print} and @code{write} members of sysfile_variable are output
00000030 0a 29 |.) |
@end example
+@node Extended Number of Cases Record
+@section Extended Number of Cases Record
+
+The file header record expresses the number of cases in the system
+file as an int32 (@pxref{File Header Record}). This record allows the
+number of cases in the system file to be expressed as a 64-bit number.
+
+@example
+int32 rec_type;
+int32 subtype;
+int32 size;
+int32 count;
+int64 unknown;
+int64 ncases64;
+@end example
+
+@table @code
+@item int32 rec_type;
+Record type. Always set to 7.
+
+@item int32 subtype;
+Record subtype. Always set to 16.
+
+@item int32 size;
+Size of each element. Always set to 8.
+
+@item int32 count;
+Number of pieces of data in the data part. Alway set to 2.
+
+@item int64 unknown;
+Meaning unknown. Always set to 1.
+
+@item int64 ncases64;
+Number of cases in the file as a 64-bit integer. Presumably this
+could be -1 to indicate that the number of cases is unknown, for the
+same reason as @code{ncases} in the file header record, but this has
+not been observed in the wild.
+@end table
+
@node Miscellaneous Informational Records
@section Miscellaneous Informational Records
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.
@item 252
End of file. This code may or may not appear at the end of the data
projects / pspp-builds.git / blobdiff