4.7.1 Attributes of Variables
Each variable has a number of attributes, including:
- An identifier, up to 64 bytes long. Each variable must have a different name.
Some system variable names begin with ‘$’, but user-defined
variables' names may not begin with ‘$’.
The final character in a variable name should not be ‘.’, because
such an identifier will be misinterpreted when it is the final token
on a line:
FOO. will be divided into two separate tokens,
‘FOO’ and ‘.’, indicating end-of-command. See Tokens.
The final character in a variable name should not be ‘_’, because
some such identifiers are used for special purposes by PSPP
As with all PSPP identifiers, variable names are not case-sensitive.
PSPP capitalizes variable names on output the same way they were
capitalized at their point of definition in the input.
- Numeric or string.
- (string variables only) String variables with a width of 8 characters or
fewer are called short string variables. Short string variables
can be used in many procedures where long string variables (those
with widths greater than 8) are not allowed.
Certain systems may consider strings longer than 8
characters to be short strings. Eight characters represents a minimum
figure for the maximum length of a short string.
- Variables in the dictionary are arranged in a specific order.
DISPLAY can be used to show this order: see DISPLAY.
- Either reinitialized to 0 or spaces for each case, or left at its
existing value. See LEAVE.
- Missing values
- Optionally, up to three values, or a range of values, or a specific
value plus a range, can be specified as user-missing values.
There is also a system-missing value that is assigned to an
observation when there is no other obvious value for that observation.
Observations with missing values are automatically excluded from
analyses. User-missing values are actual data values, while the
system-missing value is not a value at all. See Missing Observations.
- Variable label
- A string that describes the variable. See VARIABLE LABELS.
- Value label
- Optionally, these associate each possible value of the variable with a
string. See VALUE LABELS.
- Print format
- Display width, format, and (for numeric variables) number of decimal
places. This attribute does not affect how data are stored, just how
they are displayed. Example: a width of 8, with 2 decimal places.
See Input and Output Formats.
- Write format
- Similar to print format, but used by the WRITE command