In the -G lines wizard, you find a second level of -G lines which are dedicated to the fillers (for Segments only), groups, Data Elements, and Segments called the -CE Lines of a Segment.
The -G lines wizard opens from the -CE Lines tab of the Segment editor, from the Data Element call section, Segment call section, Filler definition section, and Group definition section. In this wizard, you can enter comments on -GC lines, modify error messages on -GE Lines, or customize SQL accesses on the -GG lines for the element called in a Segment.