All EntreeListItems used in your application will be added to a ListGroup. When rendered using the ListStyle "list_groups", the headers will be displayed and each group will be a seperate section.  When rendered using the ListStyle "list", the headers will be gone and all the items will be rendered flat with no seperation.

Example

EntreeListGroup lGrp = output.AddListGroup();
lGrp.ListHeader = "Hello World";