Integer Sequence Operator ‘:

The syntax first:last:step yields a row vector of consecutive integers from first to last counting by step. The final :step is optional and defaults to 1 when omitted.

Each of first, last, and step must be a scalar and should be an integer (any fractional part is discarded). Because ‘:’ has a high precedence, operands other than numeric literals must usually be parenthesized.

When step is positive (or omitted) and end < start, or if step is negative and end > start, then the result is an empty matrix. If step is 0, then PSPP reports an error.

Here are some examples:

1:6{1, 2, 3, 4, 5, 6}
1:6:2{1, 3, 5}
-1:-5:-1{-1, -2, -3, -4, -5}