Select Field or Column and then select the desired field or column.

Column Select Column if you are going to use a column for selection purposes.
Field

Select Field if you are going to use a field for selection purposes.

The ability to use a field as a selection parameter allows you to define selection criteria on fields that are not included in the report. For example, you may only want to include clients that have a zip code greater than 50000 and less than 60000 on your report, but not include the zip code field as a column on your report.

The button can be used to open the Field or Column Lookup window that allows you to view a list of fields/columns and select a field/column by double-clicking it.