You can use a separator to divide controls into subgroups within a ribbon group (see Figure 1). You can also use it in pop-up menus. In the latter case,
the separator can look like a horizontal line (see Figure 2) or a text line (see Figure 3).
Figure 1 Two separators in a ribbon group
Figure 2 Separator as a line in a pop-up menu
Figure 2 Separator as a text line in a pop-up menu