To add a single element to a List item, use the ADD_LIST_ELEMENT Built-in subprogram.
When you call ADD_LIST_ELEMENT, you indicate which List item will receive the new element by specifying the List name, List index, label, and the value to add.
In the following example, the value "1994" is added to a List item called calendar.
Add_List_Element('calendar',List_index,'1994','1994');