A sequence of ranges to specify the repetition can also be used in a special group called repeating unit with repetition ranges.
Here the repetition range is "3,5-7". The repetition count for the included structure can be: 3,5,6 or 7.
The repetition ranges consist of ranges and/or numbers separated by commas. E.g 3, 5-7
Draw the structure.
Click the Group tool on the toolbar, and select the structure to be included in the range.
In the " Create Group " dialog window choose the type " Repeating unit with repetition ranges " from the " Type " list.
Set the repetition ranges.