As described in its documentation, this function inserts something in those places where the ClauseBase grammar requires you to insert something in order to make things valid. (Without the @void, the paragraph 1. would simply be ignored because it is empty, causing the 1.1 to be set at the top level, which you obviously do not want).
However, upon printing time, the @void will be ignored by the software, not resulting in anything tangible.