In the Field List Area you see the columns divided into two main columns, where the background of the first is yellow and the background of the second is yellow. Below you see this emphasized:
The red square represent the band named Fields, while the blue square represent the band Documents. The bands have titles and those band names can reordered and removed the same way as you reorder or remove individual fields.The important part to remember is that band-titles are placed above the individual field names, and thus contains one or more columns. In the sample above, the band Fields contains the columns Fieldname and Type.