This vertical bar, located on the left-hand side of the work space, is used to define the format for each line of the report.
When initially displaying an empty report, the layout manager offers ten lines of indefinite format: "??".
To define a format, just click a line, or scan the lines to be defined: a dialog box opens, which is used to modify the corresponding format.
This dialog box is also intended for deleting or adding lines, if required.