Data types in the pivot table

The pivot table makes use of the set data types Column Selector and Order Specifier.

These set data types are defined:
Column Selector
The column selector is a comma-separated list of positive integers numbering 0 for the first column and n-1 for the last column in a table of n columns.
Example: Given a table with four columns, a column selection of "0,3,1" selects the first, the last and the second column.
Order Specifier
The order specifier is a comma-separated list of positive integers numbering 0 for the first column and n-1 for the last column in a table of n columns. Positive values specify ascending, negative values descending order.
Example: Given a table with four columns, a order specifier of "-0,3" specified an descending order on the first column and a ascending order on the last column.

There is a difference between not setting a value and specifying an empty value. The empty value always means the empty set. Not setting a value may mean selecting all or nothing, depending on the context.