A keyed collection contains an ordered collection of data elements identified by name. Because it holds key-value pairs, a keyed collection is similar to a dictionary.

Within a keyed collection, the name of each data element must be unique but the name does not have to be unique in the entire structure of data elements. For example, a keyed collection named kColl1 contains two data fields, field1 and field2 and another keyed collection, kColl2. The data fields and keyed collection cannot have the same name. However, kColl2 can have fields named field1 and field2 even though kColl1 also has fields with those names. The keyed collection data attributes "dynamic" and "description" can be overridden by another reference data.

The com.ibm.btt.base.KeyedCollection class is the implementation provided by the toolkit. The toolkit uses the <kColl> tag to externalize keyed collections.