List Item Expansion
The list type elements <ALLOWEDVALUES>, <SUGGESTEDVALUES>, and <PROHIBITEDVALUES> have two optional attributes: expanditems and filteritems.
You can assign the values true and false to expanditems; its value is true by default. When expanditems has the value of true, list items that represent groups or global lists are expanded recursively. A group's sub-groups are expanded, the sub-groups of those sub-groups are likewise expanded, and so on. After expansion, list items that represented groups include both groups and users as list item values. If expanditems is set to false, no group or global list expansion is performed.
You can assign only the value excludegroups to the filteritems attribute. When this attribute appears, all of the list items are evaluated and any groups are removed. Use the filteritems attribute to show only users, not groups.
For usage examples of the expanditems and filteritems attributes, see