Multiselection lists typically contain two parts:
The left side of the list displays the items that are available for selection. These values are defined by the allowedValues property. This property can be a list of strings, a list of XML object strings, or a list of strings returned from a call to a Java method.
The right side of the list displays the items that are currently selected. These values are set by selecting one or more items from the left side’s allowedValues list and pushing these selections to the selected list. The right side of the list is also populated when the form is loaded and the current settings are retrieved.