Level of Measurement

With SPSS, you can define the level of measurement of a variable. In most cases this is irrelevant, as SPSS will treat the variables according to the way they are declared in your statistical procedures. But there are procedures where the pre-defined level of measurement will make a difference (e.g., in multiple imputation).

VAR LEV incom age (SCALE) attitude1 to attitude5 (ORDINAL) gender (NOMINAL)

will declare "incom" and "age" as metric variable, "attitude1" to "attitude5" as variables that have an ordinal level of measurement and finally gender as a nominal variable.