Add combo list / drop down list item element at runtime in Oracle forms.

Syntax

PROCEDURE ADD_LIST_ELEMENT
(list_name VARCHAR2,
list_index, NUMBER
list_label VARCHAR2,
list_value NUMBER);

Example

Declare
  nElmntCount Number;
Begin
   -- First count the total list element currently in list item 
   nElmntCount := Get_list_element_count('yourlist');
   -- Then add it by adding + 1 to total count element 
   Add_list_element('yourlist', nElmntCount + 1, 'A Value', 'A Value');
End;

See also: http://www.foxinfotech.in/2013/04/adding-value-combolist-runtime-oforms.html