Splitting items into sections

Header (also known as separator) allows to visually split checklist into sections as presented on the screenshot below:

Add header/separator with a button

When adding new item or editing existing item there is an option so save text as a separator with the button:

 

Add header/separator without a button

When adding new item or editing existing item there is an option so save text as a separator with preceding the item text with three dashes "---":