The Sort Criteria objects extend the standard SortCollection with an easy touse, simple yet powerful and dynamic sorting capability that can sortmultiple 'columns' or 'attributes' of a collection of objects. It's easy torearrange the column sort ordering and the acending or decending state of thesort. It's simple because it just works with SortedCollections as you currentlyuse them. It's powerful because you can sort any sequence of attributes in anobject. It's dynamic as a SortCriteria and it's columns can be created on thefly by a user interface enabling the user to choose their own sort order andascending/decending sequence. The SortCriteria and SortCriteriaColumn (and SortCriteriaTest for an example)are the classes that are added to the Smalltalk system. No changes toSortedCollection were required or other Smalltalk system classes.