multi_select_listname
The working list to contain the selected entries for the list box if the allow_multi_selections property is True. The working list should contain the code field that is specified in the multi_select_codefield property.
Default value
Blank – only a single selection may be made in the list box.
Valid values
The name of a working list, in single quotes. Click the corresponding dropdown button in the property sheet to choose from a list of known working lists.