An aggregate property has a property mode other than Single Value. The property modes Page, Value List, Page List, Value Group, or Page Group are aggregate properties.
An aggregate property has one of these structures:
Value List or Page List)Value Group or Page Group)You can access a portion of an aggregate property to obtain a value or to set (assign) a new value. For example, for a Value List property, you can copy or alter the value of the tenth element. For a Page List property, you can add a new page at the end of the existing list of pages.
Use these notations and keywords to identify parts of aggregate properties. You can use these in reference directives, reference JSP tags, as parameters to the Property-Set method, and in data transforms. A few keywords such as <INSERT> are only valid in destinations, or target property references.