An indexed collection contains an ordered collection (that is, an array-type collection) of instances identified by their position in the collection. All of the data elements in the indexed collection must be the same type. For example, the data elements in an indexed collection of addresses are all instances of a keyed collection whose associated type is Address. The indexed collection data attributes "size" and "description" can be overridden by another reference data.

The com.ibm.btt.base.IndexedCollection class is the implementation provided by the toolkit. The toolkit uses the <iColl> tag to externalize indexed collections.